Syria's state media say government forces and their allies are approaching a sprawling rebel-held air base in the northwestern province of Idlib from different directions.
The fighting has seen 99,569 civilians flee southern Idlib as well as north and northeastern parts of neighboring Hama province between December 1 and Tuesday, said the U.N.'s humanitarian coordination office, UNOCHA. Assad has defeated rebels in many parts of western Syria with critical help from Russian Federation and Iran.
Russia's Defence Ministry had asked the Turkish military on Wednesday to tighten control over armed groups in Idlib after two groups of drones attacked Russian bases on January 6.
Idlib province is nearly entirely controlled by a jihadi outfit known as Hayat Tahrir al-Sham (HTS) consisting mostly of fighters from a former al-Qaida affiliate.
The activists said the warplane belonged to the Syrian army.
Turkey has been backing a substantial rebel force in Aleppo Province, just east of Idlib, and it wouldn't be surprising to hear of their involvement. "We have killed many".
Erdogan spoke to Putin on the phone, they said. A Syrian military source denied this and dismissed rebel talk of a counter attack as propaganda.
The area is part of a de-escalation zone agreement in the Kazakh capital Astana previous year between Turkey, which supports rebel groups, and Assad allies Iran and Russian Federation.
It added that the rebels had used Turkish vehicles.
Ankara is concerned that wider fighting in the province could bring tens of thousands of Syrians fleeing from the battlefields on its borders far beyond the numbers now fleeing.
Earlier in the day, an array of rebel groups in northern Syria unleashed a major counter-offensive to foil a Syrian military campaign in Idlib, following a significant advance of the government forces in that key rebel bastion.