Damascus said Thursday it is opening a corridor for civilians to leave the opposition-held northwestern region of Idlib, where government bombardment has killed hundreds since late April.
The announcement came a day after government forces recaptured the strategic Idlib province town of Khan Sheikhun from jihadists and allied rebels.
Damascus has opened such corridors out of rebel bastions in the past as a prelude to retaking them either by force or through negotiated surrenders.
The Idlib region, which sits on the Turkish border, is now the last major stronghold of opposition to the Russia-backed government of president Bashar al-Assad.
It has been controlled since January by the Hayat Tahrir al-Sham alliance, which is led by jihadists from Syria's former Al-Qaeda affiliate.
"The Syrian government announces the opening of a humanitarian corridor in Souran in the northern countryside of Hama province," state news agency SANA quoted a foreign ministry source as saying.
The corridor will be used to evacuate "civilians who want to leave areas controlled by terrorists in northern Hama and the southern countryside of Idlib", it added.
The government said it would provide shelter, food and medical care for civilians who chose to leave the region.
Footage aired on Syrian TV showed ambulances of the Syrian Red Crescent and green evacuation busses lined up in Souran.
Civilians are often wary of accepting government offers of refuge or safe passage for fear of arrest or conscription into the regime's depleted forces.
"Previous efforts to implement such corridors in southern Syria and Aleppo did little to stop the suffering of civilians and were rarely used due to fears for their safety," said Misty Buswell of the International Rescue Committee (IRC).
Wednesday's advance saw government forces cut off a pocket of territory stretching from the south of Idlib province into neighbouring Hama, the Syrian Observatory for Human Rights said.
The pocket includes the town of Morek and the nearby areas of Kfar Zita and Latamneh.
The corridor will allow their remaining residents to escape into government-held territory, the Britain-based monitor said.
But most civilians had already fled before the pocket was cut off, Observatory head Rami Abdul Rahman told AFP.
The encirclement of Morek raised the stakes between the Russian-backed government and Turkey, which has troops manning an observation post in the town.
"Neither Damascus nor Moscow is likely interested in attacking a Turkish observation point in Idlib head-on, killing Turkish soldiers and provoking a more serious incident," said Sam Heller of the International Crisis Group think tank.
"But this latest advance has shown that they can simply advance around Turkish positions if they choose, reducing those Turkish observer forces to irrelevance."
Turkey's state-run Anadolu news agency said Thursday that Syrian warplanes opened machine gun fire near one of Ankara's observation points, in the village of Al-Surman, north of Khan Sheikhun.
Turkish President Recep Tayyip Erdogan will discuss the situation in Idlib with his Russian and Iranian counterparts during a summit in Ankara on September 16, his spokesman has said.
Russian foreign ministry spokeswoman Maria Zakharova said that Moscow is continuing to collaborate with Turkey on Syria.
Kremlin spokesman Dmitry Peskov said Erdogan and Russian president Vladimir Putin could have a phone call in "the coming days".
'No life here'
The Idlib region of some three million people was supposed to be protected by a proposed buffer zone agreed by Moscow and Ankara last September.
But HTS failed to pull back from the zone and in April, government and Russian forces resumed heavy bombardment of the region.
Nearly 900 civilians have been killed since then, according to the Observatory.
More than 400,000 more have fled their homes, the United Nations says.
On Thursday, government warplanes struck villages east of Maarat al-Numan, another key town on the Damascus-Aleppo highway, the Observatory said.
The goal is to force civilians to flee ahead of a push towards the rebel-held town, it added.
Abu Hussein fled his village outside Maarat al-Numan earlier this week, after heavy bombardment.
"Towns and villages are now empty," he told AFP. "There is no life here."
The war in Syria has killed more than 370,000 people since it started in 2011 and driven millions of civilians from their homes.