The opposition and rebel withdrawal came after the Russia-backed Syrian regime forces advanced into Khan Shaykhun city in Idlib. The US urged the regime to revert to a ceasefire in Idlib after Monday's air strike on a Turkish convoy.
Syrian opposition and rebels withdrew from a town in southern Idlib province and from their last remaining territory in neighbouring Hama province after regime troops advances in the area, the Syrian Observatory for Human Rights and local activists said.
It marks an important gain for Syrian regime leader Bashar al Assad into the northwestern region, which is the last major opposition stronghold in Syria. Backed by Russia, the regime forces have been attacking the region since late April – between 500 and 700 people have been killed since.
Syrian regime forces advanced into the city of Khan Shaykhun in southern Idlib late on Monday. The city had been in the hands of anti-Assad groups since 2014.
The US urged the regime to stop the violence after an air strike on a Turkish convoy en route to observation point no. 9 in Idlib killed at least three civilians, wounded 12.
The Assad regime and its allies must return to the ceasefire in #Idlib now. Today’s reckless airstrike on a Turkish convoy follows ongoing vicious attacks against civilians, humanitarian workers, and infrastructure. We condemn this violence and it must end.— Morgan Ortagus (@statedeptspox) August 19, 2019
The opposition's territorial foothold in neighbouring Hama province dates back to the earliest days of the eight-year-long conflict. The exact death toll of Syria's war has been hard to calculate, however, the UN considers the most accurate assessment to be above 500,000.
The regime advances –– backed by Russia –– around Khan Shayhkun had threatened to encircle the opposition, militants and their allied groups in their last remaining territory in northern Hama, including the towns of Latamneh and Kafr Zeita.
The opposition forces quit those towns, local activists said.
The observatory said Syrian opposition who had stayed behind in that area had gathered at a Turkish military position in the town of Morek.
Condemning the Russian-backed regime's attack on the Turkish convoy in Maaret al Numan, Turkey's defence ministry said Moscow had been informed about the movement in advance.
Iran, Russia and Turkey agreed to create Idlib into a de-escalation zone in 2017. Russia and Turkey also agreed in September 2018 to demilitarise the southern border of Idlib, making Monday's attack all the more significant.
Site of deadly sarin attack
Khan Shaykhun was targeted by a sarin gas attack in 2017 in which over 100 people died. The chemical agent attack prompted US missile strikes against Syria.
An investigation conducted by the United Nations and the Organisation for the Prohibition of Chemical Weapons said the Syrian regime was responsible for releasing sarin on the town on April 4, 2017. Damascus denies using such weapons.
The latest Syrian regime offensive in the northwest has forced hundreds of thousands of people to flee towards the Turkish border. Turkey, which hosts some 3.6 million registered Syrian refugees and warns it can not accept more, fears the onslaught in Idlib could spark a new influx.
The US-based Union of Medical Care and Relief Organisations (UOSSM), which supports medical facilities in the northwest, says more than 730 civilians had been killed by regime or Russian forces since late April.
The UN Office for the Coordination of Humanitarian Affairs has said more than 500 civilians have died in hostilities.