( CNN ) -- Al Qaeda leader Ayman al-Zawahiri has allegedly recorded a message telling militants fighting in Syria to unite . The message , which runs more than five minutes long , was posted on militant websites . Its authenticity could not be independently verified by CNN . In the message , al-Zawahiri calls upon all jihadi factions to stop infighting . `` Our hearts are bleeding , the heart of our Islamic nation is bleeding when we see the internal strife among the mujahedeen in Syria , '' he said . `` You are the hope of our Islamic nation in establishing an Islamic governance in the lands of Syria , the chosen land of jihad . '' The words may provide verbal ammunition for Syrian President Bashar al-Assad , who has long argued that his forces are fighting `` terrorists '' in the country 's civil war . But rebels say that al-Assad allowed al Qaeda to grow in Syria in order to defame the revolution . Opinion : Syrian genocide needs justice . U.S. says it knew of photos in November . In a separate development , U.S. State Department officials told CNN on Thursday that it was November when the Obama administration found out about photos that allegedly show the Syrian regime committing mass torture . An activist showed the images to a State Department official on his laptop , officials said . But the administration did not act on the information because it did not possess the actual files , they said . The officials said they could not confirm the authenticity of the images , but they think they are genuine . CNN released a report about the existence of the photos Monday . The report , by a team of international legal and forensic experts , was based on thousands of photographs provided by a Syrian defector . The defector claimed to have worked as a photographer at a military hospital that received dead bodies from detention centers . Syria 's Justice Ministry has categorically denied the allegations , branding the report , as `` politicized and lacking in objectivity and professionalism . '' The Syrian crisis began in March 2011 , when peaceful protesters calling for reforms were met by a violent government crackdown . Dissidents began calling for the ouster of al-Assad , whose family has ruled Syria for 42 years . The conflict spiraled into a civil war that has also ratcheted up sectarian strife between Sunni and Shiite Muslims across the region . Over the past few years , foreign militants have joined both sides of the war -- including fighters from the Islamic State in Iraq and Syria and Hezbollah fighters from Lebanon . Inside Syria 's most dangerous city . CNN 's Elise Labott contributed to this report .
NEW : U.S. concerns about alleged torture photos in November , State Department officials say . A new audio recording appears to have Ayman al - Hassan telling militants to unite . ` ` You are the hope ... in establishing an Islamic governance '' in November , it says .