RIYADH, Saudi Arabia — On his eighth trip to fight with the rebels in Syria, in August, Abu Khattab saw something that troubled him: two dead children, their blood-soaked bodies sprawled on the street of a rural village near the Mediterranean coast. He knew right away that his fellow rebels had killed them. 
 
 Abu Khattab, a 43-year-old Saudi hospital administrator who was pursuing jihad on his holiday breaks, went to demand answers from his local commander, a notoriously brutal man named Abu Ayman al-Iraqi. The commander brushed him off, saying his men had killed the children “because they were not Muslims,” Abu Khattab recalled recently during an interview here. 
 
 It was only then that Abu Khattab began to believe that the jihad in Syria — where he had traveled in violation of an official Saudi ban — was not fully in accord with God’s will. But by the time he returned to Riyadh, where he now volunteers in a program to discourage others from going, his government had overcome its own scruples to become the main backer of the Syrian rebels, including many hard-line Islamists who often fight alongside militants loyal to Al Qaeda. 
 
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 The disillusionment of Abu Khattab — who asked that his full name be withheld because he still fears retribution from jihadists — helps illustrate the great challenge now facing Saudi Arabia’s rulers: how to fight an increasingly bloody and chaotic proxy war in Syria using zealot militia fighters over whom they have almost no control. 
 
 The Saudis fear the rise of Al Qaeda’s affiliates in Syria, and they have not forgotten what happened when Saudi militants who had fought in Afghanistan returned home to wage a domestic insurgency a decade ago. They officially prohibit their citizens from going to Syria for jihad, but the ban is not enforced; at least a thousand have gone, according to Interior Ministry officials, including some from prominent families. 
 
 But the Saudis are also bent on ousting Syria’s president, Bashar al-Assad, and his patron, Iran, which they see as a mortal enemy. Their only real means of fighting them is through military and financial support to the Syrian rebels. And the most effective of those rebels are Islamists whose creed — rooted in the puritanical strain of Islam practiced in Saudi Arabia — is often scarcely separable from Al Qaeda’s. 
 
 Abu Khattab, a slight-figured man with bulging eyes and the scraggly beard of an ultra-orthodox Salafist Muslim, embodies some of these paradoxes. He now volunteers here once a week to warn young men about the false glamour of the Syrian jihad at the government’s rehabilitation center for jihadists. “There is a shortage of religious conditions for jihad in Syria,” he said. Many of the fighters kill Syrian civilians, a violation of Islam, he added. 
 
 But as Abu Khattab talked about Syria, his own convictions seemed scarcely different from those of the jihadists he had carefully denounced (two officials from the Interior Ministry were present during the interview). He made clear that he considered Shiite Muslims and Mr. Assad’s Alawite sect to be infidels and a terrible danger to his own people. 
 
 “If the Shiites succeed in controlling Syria, it will be a threat to my country,” Abu Khattab said. “I went to Syria to protect my country.” 
 
 At times, his sectarian feelings seemed to outshine his unease about the excesses of some of his more extreme comrades. He did not deny that he had often fought alongside members of the Islamic State of Iraq and Syria, or ISIS, the brutal jihadist group affiliated with Al Qaeda. 
 
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 Abu Khattab also mentioned proudly that he is no stranger to jihad. He fought as a teenager in Afghanistan (“With the government’s permission!”) and, a few years later, in Bosnia. He chose not to fight the Americans in Iraq “because there are too many Shiites there,” he said, with a look of distaste on his face. 
 
 Yet this is a man who lectures inmates at the rehabilitation center every week about ethics and war. The center, like many Saudi institutions, has been somewhat embarrassed by the contradictions of Saudi policy with regard to Syria. Although the center incarcerates some men who have been arrested for trying to travel to Syria, last summer the nephew of Abdelrahman al-Hadlaq, its director, was killed while fighting there. His mother posted statements on Twitter saying she was proud of him. 
 
 More recently, the center suffered an even more stinging disappointment involving one of its best-known graduates, a reformed jihadist named Ahmed al-Shayea. He became famous in Saudi Arabia after surviving his own suicide bombing in Iraq in 2004, a bombing arranged by militants with Al Qaeda’s Iraqi branch. 
 
 Mr. Shayea was burned and disfigured, but after months in a hospital he emerged and proclaimed himself cured of the jihadist mind-set. He was known as the “living suicide,” and in 2009 an American author, Ken Ballen, devoted an entire chapter to a glowing portrait of him in his book, “Terrorists in Love.” 
 
 In November, Mr. Shayea slipped out of Saudi Arabia to Syria, where he is now fighting with the Islamic State of Iraq and Syria. He proudly trumpets his return to jihad on his Twitter feed, which features a picture of him clutching a rifle with his mangled hands. 
 
 The Saudi authorities say they have urged their citizens not to go to Syria, but cannot keep track of every Saudi who wants to go fight there. “We try to prevent it, but there are limits to what we can do,” said Mansour al-Turki, a spokesman for the Saudi Interior Ministry. “You cannot prevent all young men from leaving the kingdom. Many of them travel to London or other places, and only then to Turkey, and Syria.” 
 
 Abu Khattab’s path to Syria was similar to that of many others here and across the Arab world. He read about the uprisings in 2011, but it was Syria that touched his heart. It was not just because of the bloodshed, he said, but because his Sunni brothers were being killed by Alawites and Shiites. 
 
 When he first went, in the summer of 2012, he flew directly from Riyadh to the Turkish city of Antakya, near the Syrian border, he said. There were other Saudi men heading for the battlefield on the flight with him, he said, and no sign of a Saudi government effort to monitor or restrain them. 
 
 In Turkey, he found many other foreign fighters, and Syrian rebels who were eager to take them to the battlefield. “They especially like Saudis, because the Saudis are more willing to do suicide operations,” he said. 
 
 Over the next year, Abu Khattab said, he returned to Syria seven more times, usually on holidays, leaving his wife to care for their four children and staying for 10 days to two weeks each time. He fought with a variety of groups, seeing battle many times — in Aleppo, in Homs and in the countryside of Latakia, near the coast. He wielded a Kalashnikov rifle most of the time, but sometimes a heavier Russian-made machine gun known in the field as a 14.5. 
 
 Gradually he became disillusioned with the chaos of the battle. He often found himself among men who openly branded the rulers of Saudi Arabia and other Persian Gulf states as infidels, deserving slaughter. He said this bothered him, but it did not stop him from returning to the battlefield. 
 
 In the end, it was the slaughter of innocents that made him decide to quit, he said, and a broader feeling that the rebels alongside him were not doing it for the right reasons. “If the fight is not purely to God, it’s not a real jihad,” he said. “These people are fighting for their flags.” 
 
 But there was another reason he gave up the fight. 
 
 “Bashar has started to put Sunnis on the front line,” he said of Syria’s leader. “This is a big problem. The rebels do not want to fight them. The real war is not against Bashar himself, it is against Iran. Everything else is just a false image.” ||||| Photo 
 
 BEIRUT, Lebanon — The leader of the Nusra Front, an affiliate of Al Qaeda in Syria, on Tuesday proposed an initiative aimed at halting the worst infighting yet between the armed opponents of President Bashar al-Assad since the start of the conflict nearly three years ago. 
 
 Deadly battles have raged in recent days across northern Syria between rebel forces and another Qaeda affiliate, known as the Islamic State of Iraq and Syria, or ISIS, that also wants to depose Mr. Assad’s government but aims to replace it with a monolithic Sunni extremist government that rules both countries. 
 
 Angered by what they call the tendency of the Islamic State of Iraq and Syria to commandeer resources, impose strict social codes, and kidnap and kill opponents, rebel groups have been attacking its bases and trying to drive out its fighters from towns and villages where they once held sway. 
 
 More than 270 people had been killed in four days of fighting as of Monday, according to the Syrian Observatory for Human Rights, an opposition group based in Britain with a network of contacts in Syria. The dead include 46 civilians, 129 rebel fighters and 99 fighters for the Islamic State of Iraq and Syria. Both sides have also executed prisoners, the Syrian Observatory said. 
 
 In an audio recording released online on Tuesday, the head of the Nusra Front, known as Abu Mohammed al-Jolani, said the infighting resulted from the “incorrect policies” of the Islamic State of Iraq and Syria. He called for a cease-fire and the establishment of an Islamic court to handle disputes, saying the violence could give Mr. Assad’s forces the opportunity to regain territory. 
 
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 “The whole battlefield, including the foreign and local fighters, will pay the price of losing a great jihad because the regime will rebound when it was so close to vanishing,” he said. 
 
 While rebel forces have in the past established Islamic courts to administer individual towns and villages, the movement has never had a unified leadership that could impose discipline. 
 
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 The authenticity of the Nusra Front leader’s statement could not be immediately confirmed. 
 
 The Syrian Observatory has reported that more than 130,000 people have been killed since the conflict began in March 2011. But the United Nations, which has been saying for months that the death toll has exceeded 100,000, announced on Tuesday that it had decided to stop updating its own tally, at least for the foreseeable future, because of the problems in verifying information. 
 
 “It was always very close to the edge in terms of how much we could guarantee the source material was accurate,” Rupert Colville, a spokesman for the United Nations high commissioner for human rights, told reporters in Geneva. He partly attributed the decision to the extremely limited ability of the United Nations to independently conduct fact-finding in Syria, making it “increasingly difficult for us to source and analyze the casualty figures in order to update them.” 
 
 Suspension of a United Nations update on casualties “will be a loss — we will now have only disparate sources of information,” said Hamit Dardagan, an author of a report on Syrian casualties by the Oxford Research Group, a London-based organization that put the toll at 113,700 as of November. 
 
 Mr. Dardagan, a founder of Iraq Body Count, a project begun in 2003 to record civilian casualties from the war in Iraq, also said the sectarian nature of the Syrian crisis would further complicate any data collection. “As any conflict intensifies and you have more refugee flows and more people displaced, that becomes more difficult,” he said in an interview. 
 
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 The number of nongovernmental organizations able to work in Syria has been reduced by the increasing violence. Civilian groups that report events considered unfavorable to any of the warring parties have been targeted; most recently, Razan Zeitouneh, a rights activist who ran the Violations Documentation Center, and her colleagues were abducted from their office in a Damascus suburb. Parties on both sides also actively filter information they provide to the outside world to help their cause, and government restrictions and the threat of kidnapping and death have severely limited access for journalists. 
 
 United Nations agencies that do have some access have also described problems in verifying data. Officials with the World Food Program and the World Health Organization in Damascus said recently that because their officials could not reach many areas in Syria, they had set up local contacts to relay information to them, but that verification was difficult. Government ministries provide some data, but they are out of touch with branches in some rebel-held areas. 
 
 The United Nations reported some progress on Tuesday in the international effort to purge Syria’s chemical weapons stockpile. In a statement issued with the Organization for the Prohibition of Chemical Weapons, it said the first batch of the most dangerous materials in the stockpile had been exported from the country, loaded onto a Danish commercial vessel in the Syrian port of Latakia. 
 
 The statement said the Danish vessel would remain at sea until the second cargo of chemicals reached Latakia, when it would return to load them. The vessel was escorted by Danish and Norwegian naval vessels, the statement said, and China and Russia were providing further maritime security for the operation. 
 
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 “This movement initiates the process of transfer of chemical materials from the Syrian Arab Republic to locations outside its territory for destruction,” said the statement by Sigrid Kaag, the United Nations official responsible for coordinating the effort. 
 
 The export and destruction of the most dangerous substances in the Syrian arsenal, which the statement called “priority chemical materials,” has long been considered the trickiest and most hazardous part of the operation, which Syria agreed to carry out as part of its pledge more than three months ago to renounce chemical weapons and join the treaty that bans them. 
 
 Under a Security Council resolution approved Sept. 27, all of Syria’s chemical weapons must be destroyed by the middle of 2014. The most dangerous chemicals were supposed to have been exported from the country by Dec. 31, but that stage of the operation was delayed because the war had made their overland transport to Latakia too dangerous to complete. ||||| BEIRUT (AP) — Syrian rebels on Wednesday seized control of a hospital in the northern city of Aleppo that was used as a base for the area by their al-Qaida rivals, activists said. 
 
 In this Monday, Jan. 6, 2014 citizen journalism image provided by Aleppo Media Center, AMC, which has been authenticated based on its contents and other AP reporting, Syrians hold copies of the Quran,... (Associated Press) 
 
 The capture of the hospital was a boost for the rebels, who only the day before saw 20 of their fighters killed in an al-Qaida suicide car bombing in the northern city of Darkoush, said the British-based Syrian Observatory for Human Rights. 
 
 It also underscores the intensity of the rebel infighting that has raged for days between Syrian rebels and their one-time allies, fighters from the extremist Islamic State in Iraq and the Levant. 
 
 Also in Aleppo, the Observatory said a series of government airstrikes in two rebel-held suburbs late on Tuesday night killed 19 people. There were no further details. The government in Damascus did not comment on the bombings. 
 
 The two main rebel camps in Syria fighting against President Bashar Assad's troops — a chaotic array of rebel brigades and the al-Qaida-linked group — turned their guns on each other last Friday. The clashes have since become the most serious rebel infighting since the uprising against Assad began in March 2011. 
 
 The rebel-on-rebel fighting began after tensions, which had simmered for months, erupted into the open after reports that the al-Qaida fighters had tortured and killed a popular doctor. 
 
 It has since spread from the northern province of Aleppo to nearby Idlib and to the province of Raqqa. At least 300 people have been killed in the infighting, said Rami Abdurrahman, the head of the Observatory. 
 
 The clashes add another layer of complexity to the Syrian conflict, less than three weeks ahead of a planned international peace conference to try to resolve the civil war. 
 
 Syrian rebels seized the hospital in Aleppo's Qadi Askar quarter that the al-Qaida fighters had overrun months ago and used as their main compound or base for the area, said the Observatory, which relies on a network of activists on the ground. 
 
 The Observatory said there were reports, still unconfirmed, that dozens of detainees held by the extremists had been freed. 
 
 One of the most pressing issues in the rebel infighting is the fate of dozens of Syrian and foreign reporters, media activists, aid workers and civilians abducted and held by the al-Qaida fighters since they fanned into the area in March. 
 
 There are fears for the fate of the detainees as the fighting rages and as the al-Qaida group seeks to extoll revenge on their rivals. 
 
 On Tuesday, the Observatory and other groups reported that at least four activists detained in the Aleppo hospital had been killed. 
 
 As the rebel infighting continued, so did clashes between Assad's forces and rebels. 
 
 In Douma, a town close to the Syrian capital of Damascus, three people and a child were killed and several were wounded after a government airstrike targeted a house on Tuesday, reported the Observatory and another activist group, the Local Coordination Committees. 
 
 Dramatic footage of the aftermath of the strike was uploaded to social media networks. It corresponded with the Associated Press' reporting of the event. 
 
 "Be patient, little one, be patient!" a man is seen in one video, calling out to a child who was heard wailing under the rubble of a smashed house. Other men are seen furiously digging to pull out the victims. 
 
 Minutes later, a toddler screams as he is seen being pulled out from under the rubble. Another man is seen carrying a dust-covered, lifeless small body to nearby medics who then try to resuscitate the child.
– Syrian rebels are locked in a bitter and violent struggle—with each other. Hostilities between Syria's more moderate rebel factions and the al-Qaeda-affiliated Islamic State of Iraq and Syria exploded into open warfare on Friday, and it's been so costly that the head of another al-Qaeda affiliate, the al-Nusra Front, is calling for an Islamic court to be set up to settle disagreements, the New York Times reports. Abu Mohammed al-Jolani said the fighting was the result of the "incorrect policies" of the ISIS, but that if there wasn't a ceasefire soon, "the whole battlefield … will pay the price of losing a great jihad." Other rebels accuse the ISIS—which wants to combine Iraq and Syria into one Sunni-ruled country—of hogging resources, applying strict social codes, and kidnapping and killing its foes. So far at least 300 people have died in the rebel in-fighting since Friday, including dozens of civilians, according to the Syrian Observatory for Human Rights, and rebels today captured a hospital-turned-ISIS base in Aleppo, the AP reports. The infighting also highlights a challenge for Saudi Arabia, which is backing the rebels in hopes of ousting Assad's Shiite, Iran-affiliated regime, but is uneasy about the potential for jihadist spill-over, the Times adds.