The UN Commission of Inquiry on the rights situation in Syria said in its latest report on Monday it had evidence that Russian planes participated in two air strikes in Idlib and in rural Damascus last July and August that killed more than 60 people.

The UN report, which covers the period from July 2019 to January 10 this year, said there was evidence to prove Russian planes took part in both attacks, and that since they were not directed at military objectives they amounted to a "war crime".

"We do not agree with such accusations," Kremlin spokesman Dmitry Peskov told reporters, raising questions about the objectivity of the report.

"It is obvious that no commission could have received reliable information on what is happening on the ground," Peskov said.

He added: "Nothing is said about the attacks by terrorist groups, which makes any judgement issued by this commission one-sided."

The UN's Syria commission, set up in 2011 shortly after the civil war began, has repeatedly accused various sides of war crimes and in some cases crimes against humanity.

The allegations against Moscow came against the backdrop of a sharp rise in tensions between Turkey and the Russian-backed Syrian military, which is fighting to recapture the last bastion of opposition to President Bashar al-Assad in northern Syria.

The escalation has sparked a humanitarian crisis and a political standoff between Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan, who is travelling to Russia on Thursday to discuss the conflict.

More than 380,000 have been killed in the fighting in Syria since a series of street protests against Assad's rule in 2011 disintegrated into a proxy conflict drawing in countries throughout the Middle East.