Some militants have withdrawn from the demilitarisation zone in Idlib following a deal between Russia and Turkey on the northwestern Syrian region, a US official said on Wednesday.

Syria's army Friday warned residents of the country's last major rebel bastion to stay away from jihadists, who have yet to withdraw from a buffer zone ahead of a looming deadline.

Syrian rebels completed the withdrawal of heavy weapons from the frontline in Idlib on Monday, under the deal between Russia and Turkey to create a demilitarised zone, the state-owned Anadolu news agency said.

Syrian rebels denied on Sunday they had pulled any heavy arms from a major opposition bastion in the north, as the deadline to implement a demilitarisation deal there draws closer.

The Syrian Observatory for Human Rights said on Sunday that rebel group Failaq al-Sham has started withdrawing its forces and heavy arms from a demilitarised zone in northwest Syria.

The Syrian state will recover Idlib through war or peaceful means, a minister was quoted as saying on Tuesday, pointing to the government's determination to defeat rebels there despite a Russian-Turkish deal that halted an expected army offensive.

Turkey will take action east of the Euphrates river in Syria and impose secure zones as it has done in the northwest of the country, President Tayyip Erdogan said in comments broadcast on Turkish media on Monday.

Rebels have cautiously accepted a Moscow-Ankara deal to prevent a Russia-backed regime attack on Syria's last major opposition bastion of Idlib, while a small jihadist group has rejected it.

Around 7,000 people from Syria's Hama and Idlib provinces have returned to their homes after an agreement by Turkey and Russia to set up a demilitarized zone in Idlib, a monitoring group said Wednesday.

Turkey, which supports rebels opposed to Syrian President Bashar al-Assad, has been holding talks with his allies Russia and Iran over the fate of Idlib.

United Nations Secretary-General Antonio Guterres on Tuesday appealed to Russia, Iran and Turkey to "spare no effort to find solutions that protect civilians" in Syria's Idlib and said it was "absolutely essential" a full-scale battle was avoided.

Qatar Red Crescent Society (QRCS) has said it is developing an emergency response plan to deal with a potential mass displacement movement in the northern parts of Syria.