Free Syrian Army fighters lay cover fire after what they say was during clashes with forces loyal to President Bashar al-Assad in Deir al-Zor on May 13, 2013.

Beirut -

The Free Syrian Army vowed on Wednesday to punish those committing atrocities, as anger mounted at a video showing a rebel filmed apparently cutting out and eating the organs of a soldier.

“Any act contrary to the values that the Syrian people have paid their blood and lost their homes to will not be tolerated, the abuser will be punished severely even if they are associated with the Free Syrian Army,” the main rebel group said in a statement.

The gruesome video has thrown the spotlight on war crimes allegations against the opposition and put the mainstream rebel leadership and its backers on the defensive.

The Free Syrian Army said field commanders had been instructed “to begin a prompt investigation into the matter in which the perpetrator will be brought to justice”.

Investigations would also be held into whether the rebel in the video is a member of the Free Syrian Army or not, it said.

Time magazine reported that the Syrian rebel at the centre of the row has defended his actions as revenge for regime atrocities.

The magazine said it had talked by Skype with the fighter in the video, whom it identified as Khalid al-Hamad.

Hamad claimed he was driven to the gruesome acts by footage on the dead soldier's cellphone, showing him “humiliating” a naked woman and her two daughters.

The US news weekly said Hamad described participating in other acts of mutilating regime forces, including militiamen known as shabiha.

The video, in which Hamad leans over a uniformed body, cuts out organs and then holds one up to his mouth, has prompted an outcry around the world. - Sapa-AFP