(Recasts with monitor and rebel statements)
BEIRUT, Aug 20 (Reuters) - A Syrian war monitor said rebels had withdrawn from a town in southern Idlib province and from their last territory in neighbouring Hama province after government advances, though an insurgent group denied this and said they were still fighting.
The recovery of these areas would mark an important gain for President Bashar al-Assad into the northwestern region which is the last major rebel stronghold in Syria.
The Syrian Observatory for Human Rights and local activists said insurgents had withdrawn from the town, Khan Sheikhoun, after fierce bombardment.
The most powerful insurgent group in the area, the jihadist Hayat Tahrir al-Sham, however said rebels still held part of Khan Sheikhoun and areas in northern Hama despite what it described as a redeployment in the town after fierce enemy bombardment.
There was no immediate comment from Syrian state media.
Syrian government forces stepped up military operations against the northwestern region in late April, an offensive that has killed hundreds of people and forced hundreds of thousands of people to flee towards the Turkish border.
Assad has defeated his rebel opponents across much of the country with help from Russian and Iran-backed forces.
Khan Sheikhoun has been in rebel hands since 2014. The opposition's territorial foothold in neighbouring Hama province dates back to the earliest days of the eight-year-long conflict.
Russian-backed Syrian government advances around Khan Sheikhoun had threatened to encircle rebel fighters in their last remaining territory in northern Hama, including the towns of Latamneh and Kafr Zeita.
Local activists and the Observatory said the rebels had quit those towns.
The Observatory said Syrian rebels who had stayed behind in that area had gathered at a Turkish military position in the town of Morek, in the territory abandoned by the rebels.
Turkey, which backs some of the rebel groups in the northwest, has established a dozen military positions in the area under agreements with Russia. One of its main concerns is to prevent a further influx of Syrian refugees fleeing government control, 3.6 million of whom already live in Turkey.
A Turkish military convoy was targeted in an air strike in the northwest on Monday after it entered the territory. Rebel sources said the Syrian government had targeted it.
Syrian state media said the despatch of the convoy into Syria was an act of aggression and it had entered to help insurgents fighting an army advance in Khan Sheikhoun.
Khan Sheikhoun was targeted in a sarin gas attack in 2017 that prompted U.S. missile strikes against Syria.
An investigation conducted by the United Nations and the Organisation for the Prohibition of Chemical Weapons said the Syrian government was responsible for releasing sarin on the town on April 4, 2017. Damascus denies using such weapons.
The latest Syrian government offensive in the northwest has forced hundreds of thousands of people to flee towards the Turkish border.
The U.S.-based Union of Medical Care and Relief Organizations (UOSSM), which supports medical facilities in the northwest, says more than 730 civilians had been killed by government or Russian forces since late April.
The U.N. Office for the Coordination of Humanitarian Affairs has said more than 500 civilians have died in hostilities. (Writing by Tom Perry Editing by Andrew Heavens)
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