Coffins carrying the bodies of some of the people who were killed on Thursday in drone attack on a military academy. Reuters

An attack on Thursday on a Syrian military academy killed more than 110 people, a war monitor said, with state media blaming "terrorist organisations" for the drone strike in government-held Homs.

Separately, Turkish air raids in the country's Kurdish-held northeast killed at least 11 people, according to Kurdish forces, after Ankara had threatened retaliation for a bomb attack.

In the central city of Homs, "armed terrorist organisations" targeted "the graduation ceremony for officers of the military academy", an army statement carried by official news agency SANA said.

The Syrian Observatory for Human Rights, a Britain-based monitor, reported "112 dead including 21 civilians, 11 of them women and girls". It said at least 120 people were wounded.

Health Minister Hassan al-Ghobash told state television the "preliminary" toll was 80 dead "including six women and six children" and around 240 wounded.

There was no immediate claim of responsibility.

The attack was carried out with "explosive-laden drones", according to the military statement, vowing to "respond with full force".

The government declared three days of mourning starting Friday.

In the rebel-held Idlib region, residents reported heavy bombardment by government forces in apparent retaliation. The Observatory said eight people had been killed and some 30 wounded.

United Nations chief Antonio Guterres "is deeply concerned about the drone attack", his spokesman Stephane Dujarric said. He "is also deeply concerned about reports of retaliatory shelling" in northwestern Syria, Dujarric added.

Overnight, Syrian shelling killed an elderly woman and four of her children in a rebel-held area of Aleppo province, rescue workers and the Observatory said.

Agence-France Presse