Civilians have been caught in the crossfire; activists estimate that more than 14,000 people have been killed since the start of the uprising against President Bashar Assad's regime.

In a desperate bid to end the violence after an earlier peace plan failed to do so, U.N. envoy Kofi Annan said that Iran — one of Syria's most loyal allies — should be part of the solution to the conflict.

Syria's state-run news agency, SANA, said the dead found in the rebel-held area of Daret Azzeh near Aleppo were killed and their bodies mutilated by terrorist groups. The government refers to rebels as terrorists.

The amateur video showing the corpses appeared to back up the allegation of a mass killing.

"The terrorist groups in Daret Azzeh committed a brutal massacre against the citizens, whom they had kidnapped earlier in the day," SANA said.

The report said at least 25 people were killed, but others were missing.