( CNN ) -- Yemen 's embattled president told the country 's largest opposition bloc he would step down at the beginning of next year , a ruling party official told CNN . The opposition rejected the offer , demanding that Ali Abdullah Saleh resign immediately . Saleh pushed back against opponents including some of his own top generals Tuesday , defying calls for him to quit . `` Those who want to reach power through a coup will be unable to . This is impossible . The scenario will turn into a civil war , '' Saleh said in a televised speech . `` There is a constitution , and there are rules . There is the will of the people . It is impossible for a minority to control the fate of the nation , '' he said . Also Tuesday , Yemen 's army repelled an attack on a military position by al Qaeda in the Arabian Peninsula , killing 12 militants and wounding five , a Yemeni official told CNN , citing sources at the Interior Ministry in Sanaa . The official , who spoke on condition of not being named because he is not authorized to talk to the media , said the attack occurred east of the city of Lawdar , in Abyan province in southwest Yemen . Saleh , who has been in power for 32 years , has been a key U.S. ally as al Qaeda turns his country into a base . It is not clear when Saleh made his offer to step down in 2012 to the opposition JMP bloc , the largest opposition group , but they rejected his speech Tuesday . `` Any offer that does not include the president 's immediate resignation is rejected , '' said Mohammed Qahtan , a JMP spokesman . The president 's defiant speech came a day after Saleh met a top general who announced he was supporting the protests that have been roiling Yemen since the beginning of the year . Even officials in Saleh 's own party expressed worries about the speech , which came on the heels of a particularly tense day in Yemen . `` It will cause more concern , and I think this will only increase the tension , '' ruling party official Mohammed Abulahoum told CNN . `` I hope that the military and the police and all units will not obey any order of any individual that asks them to point their guns at their people . After all , they are there to defend the people , '' he said . Some government officials and others have declared their support for the opposition in the wake of a government crackdown on protesters that left 52 people dead last week . On Tuesday , Rupert Colville of the United Nations Office of the High Commissioner for Human Rights expressed concern about the situation in Yemen . The agency deplored the reported killings of protesters , including allegations of snipers shooting from rooftops , Colville told a news briefing in Geneva . `` All such violations of human rights must indeed be investigated by independent and impartial mechanisms , '' Colville said . Saleh and Maj. Gen. Ali Mohsen Al-Ahmar on Monday discussed a deal for a peaceful transition of power that would allow Salehto to stay in place for the rest of the year , a Yemeni official and senior U.S. official said . Then on Tuesday , Saleh appeared to criticize the powerful general and other officers who declared their support for the opposition on Monday , saying , `` Any division in the military will have negative impacts on the whole country . '' A government official said the speech was a warning to those who broke ranks . `` Saleh was sending a message to the generals who defected yesterday , telling them , you know you 're going to come back , so why not come back now rather than trying to do so later ? '' said the official , who asked not to be named because of the sensitive situation . Al-Ahmar , who belongs to an important tribe whose backing is significant for Saleh , said Monday he would order his troops to protect civilians demonstrating against the president . A wave of other officials announced their support for the opposition Monday . They included Yemen 's ambassador to Britain and the embassy 's entire diplomatic staff , as well as Yemen 's ambassador to the European Union , Mohamed Jaffer . U.S. Defense Secretary Robert Gates said Tuesday the United States was `` obviously concerned about the instability in Yemen . We consider al Qaeda in the Arabian Peninsula , which is largely located in Yemen , to be perhaps the most dangerous of all the franchises of al Qaeda right now . '' Radical American-born cleric Anwar al-Awlaki is believed to be hiding in the country . The cleric has been linked to terror plots including the attempt to bomb a Detroit-bound plane on Christmas Day 2009 , and he corresponded separately with a British Airways employee about trying to smuggle explosives onto planes . Top American officials , including U.S. President Barack Obama 's counterterrorism chief , have traveled to Yemen to meet with Saleh . Leaked diplomatic cables suggest Saleh 's government helped disguise strikes by U.S. unmanned drones on terror targets in Yemen by calling them Yemeni actions . CNN 's Tracy Doueiry , Caroline Faraj , Elise Labott , Richard Roth , Pam Benson and Jo Shelley and journalist Hakim Almasmari contributed to this report .
Yemen : Source says military kills 12 Al - Qaeda militants in repelling an attack . U.N. official criticizes attacks on protesters . President Saleh makes an appeal to the opposition , a ruling party official says . The opposition demands he step down immediately .