The buffer zone agreed last month between Ankara and Moscow aims to separate regime fighters from the myriad insurgent and extremist forces of the Idlib region.
Syria rebels say they have started withdrawal of heavy arms from Idlib buffer zone
Syrian rebels said on Saturday they have begun withdrawing heavy arms from a planned buffer zone in northwestern Idlib province, ahead of a deadline to set up a demilitarised area.
The Turkey-backed National Liberation Front (NLF) "has started pulling out its heavy weapons from the zone", the rebel coalition's spokesman Naji Mustafa told AFP.
The buffer zone, agreed last month between rebel-backing Ankara and government ally Moscow, aims to separate regime fighters from the myriad insurgent and extremist forces of the Idlib region.
The accord aims to stave off a massive regime assault on the last major rebel bastion by creating a 15 to 20-kilometre buffer zone ringing the area.
Under the deal, all rebels in the demilitarised zone must withdraw heavy arms by October 10, and hardline rebel groups must leave by October 15.
Mustafa said the rebel coalition was "maintaining its positions and headquarters with medium and light weapons" inside the buffer zone.
A representative for Faylaq al-Sham, one of the groups making up the alliance, confirmed the withdrawal of arms including missile launchers and mortar cannons had begun.
The British-based Syrian Observatory for Human Rights said it had information that the weaponry was pulled out Friday evening, and on previous days, but that the rebels did not publicise the move.
The NLF is the main Turkey-backed rebel alliance in the Idlib region, but extremist heavyweight Hayat Tahrir al-Sham (HTS) holds most of the province.
HTS, led by former Al-Qaeda fighters, has yet to announce its stance on the buffer zone deal.
Fighting erupted on Friday between Ankara-backed rebels and hardliners near the planned demilitarisation zone, a monitor said.
The Observatory war monitor said violence first flared between HTS and Nour al-Din al-Zinki rebels in the town of Kafr Halab.
HTS had reportedly been trying to arrest a local commander in the town on the western edge of Aleppo province, near the administrative border with Idlib.
"Zinki sent reinforcements to the area, and the clashes expanded to several areas and the National Liberation Front joined in," said Observatory head Rami Abdel Rahman.
At least three civilians and six fighters were killed, the monitor said, before calm was restored after a truce deal between the factions.
Many of the details of the buffer zone agreement, including where exactly the area should fall, remain unclear.
The NLF has refused any Russian presence in the buffer zone, which President Vladimir Putin said would be monitored by Russian military police and Turkish troops under the agreement.
Moscow has accused HTS and other "radical fighters" of trying to torpedo the accord.
Russian foreign ministry spokesman Maria Zakharova said on Thursday that they "fear finding themselves isolated by the Russian-Turkey deal, and are committing all sorts of provocations and aggravating the situation".
Syria's conflict has killed more than 350,000 people and forced millions more out of their homes, while the UN has warned a full-blown regime attack on Idlib could bring unprecedented suffering.