Syrian opposition fighters on Thursday (February 27th) reentered a key north-western town they had lost earlier this month, reversing one of the main gains of the government's devastating offensive in the region.

The counter-offensive could be short-lived, however, and Russian-backed Syrian troops continued to chip away at other parts of the opposition bastion, ignoring growing appeals for a ceasefire.

The UN Security Council, where Moscow has systematically vetoed truce initiatives, was due to meet again on Thursday amid growing concern Idlib was witnessing the nine-year-old war's worst humanitarian emergency yet.

On Thursday, extremists and Turkish-backed opposition fighters managed to reenter Saraqeb, a key crossroads town in Idlib province they had lost earlier in February.

State news agency SANA acknowledged that there were "fierce clashes" between the army and "terrorist groups on the Saraqeb front".

An AFP correspondent accompanied the opposition fighters into Saraqeb, where he found a ghost town of bombed out buildings deserted by its inhabitants.

The correspondent saw fighters deploy inside the town in large numbers, where they come under attack from government forces on the outskirts as well as from the air.

The Syrian Observatory for Human Rights said the airstrikes were carried out by Russia, which has come under heavy criticism for the high civilian death toll from its bombing campaign.

State media accused the "terrorists" of launching car bombings and other suicide attacks against government forces attempting to retake the town which they had held since February 8th.

It said the army had inflicted heavy losses on the attackers, despite the military support it said they had received from Turkey.

The Turkish defence ministry said on Thursday that two of its soldiers had been killed by government fire in Idlib, taking its losses this month alone to 19.

Turkey immediately responded to the attack by hitting Syrian "regime targets", the ministry said on Twitter.

President Recep Tayyip Erdogan warned the Syrian government on Wednesday to "stop its attacks as soon as possible" and to pull back by the end of the month.