Damascus: A drone attack on a military college in Syria's Homs province during a graduation ceremony has killed as many as 80 people and wounded 240 others, the Syrian health minister has said, Al Jazeera reported.

Health Minister Hassan al-Ghabash said that civilians, including six children, and military personnel were among those killed. There were concerns that the death toll could rise further as many of the wounded were in serious condition.

There was no immediate claim of responsibility for the attack.

The country's military said drones laden with explosives targeted the ceremony on Thursday as it came to an end. In a statement, the military accused fighters "backed by known international forces" for the attack.

UN Secretary-General Antonio Guterres "expressed deep concern" at the drone attack in Homs as well as "reports of retaliatory shelling" in northwest Syria, his spokesperson Stephane Dujarric said.

Syria's defence minister attended the graduation ceremony but left minutes before the attack.

"After the ceremony, people went down to the courtyard and the explosives hit. We don't know where it came from, and corpses littered the ground," said a Syrian man who had helped set up decorations at the ceremony.