Beirut (AFP) - A planned buffer zone in northwest Syria has been cleared of heavy armaments ahead of time but a new deadline loomed Wednesday for the tougher task of Turkey convincing jihadists to pull out their fighters.

The demilitarised zone ringing the Idlib region is the result of a deal reached last month between rebel backer Turkey and government ally Russia to stave off a regime assault on Syria's last major rebel stronghold.

The accord called for a complete withdrawal of all heavy weapons from the planned buffer by Wednesday, and rebels and jihadists met that deadline a day early.

"No heavy weapons were seen in the buffer zone," said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

The Turkey-backed National Liberation Front (NLF) rebel alliance said it had pulled out all heavy arms by Monday, and the Observatory said jihadists quietly followed suit.

In the days leading up to the deadline, AFP journalists saw heavy weaponry, including tanks and artillery, that had been withdrawn from the zone and restationed elsewhere in Idlib.

Despite the relatively speedy implementation of the accord's first deadline, observers say a thornier task lies ahead.

Under the deal, the zone must be free by next Monday of all jihadists, including those of Hayat Tahrir al-Sham (HTS), the region's dominant force led by former Al-Qaeda fighters.

With five days to go, HTS and other jihadist fighters remained inside the planned buffer area and showed no sign of leaving.

- 'Harder point' -

HTS, which controls more than half of the Idlib region, has not officially responded to the Turkey-Russia deal.

Haid Haid, an associate fellow at Chatham House, said Turkey persuading the jihadists to move out was always going to be the toughest part of the deal.

"Of course implementing the heavy weapons point is easier," he said.

"The harder point is withdrawing forces from the area."

Syrian Foreign Minister Walid Muallem had expressed confidence in Turkey's ability to fulfil its side of the deal "because of its knowledge of factions" on the ground.

Story continues

HTS, jihadists from the Turkestan Islamic Party (TIP) and current Al-Qaeda outfit Hurras al-Deen control more than two-thirds of the planned buffer zone.

Many of HTS's fighters have battled for years in Syria under various groups and are keen to keep their influence in the war-ravaged country's largest remaining rebel bastion.

"HTS is playing the long game in Idlib," said Nicholas Heras of the Center for a New American Security.

"It is making the assessment that Turkey will allow it to continue to operate in northwest Syria, so long as HTS keeps a low profile," he added.

"As long as HTS stays on Turkey's good side, it has a golden opportunity to set permanent roots in Idlib," Heras said.

- 'Freeze the war' -

In recent weeks, Turkey has dispatched convoys of troops to monitoring posts in the region and its soldiers are expected to patrol any future buffer zone.

Forces loyal to President Bashar al-Assad have retaken large parts of Syria from opposition fighters and jihadists since Russia intervened in September 2015.

After a series of victories near Damascus and in the south of the country earlier this year, a similar Moscow-backed assault had been expected against Idlib before the Russia-Turkey deal was announced.

Despite progress in implementing the accord, Assad insisted on Sunday it was a "temporary measure" and that Idlib would eventually return to state control.

Heras said that, with the buffer zone accord, Russia sought to hand over the burden of dealing with powerful jihadists to Turkey.

"The Russians want to freeze the war in western Syria and get on with the business of rebuilding Assad's zone of control," Heras said.

"Assad might want to reconquer Idlib, but for now he does not have a better option than this deal," he said.

The Syrian war has killed more than 360,000 people since it erupted in 2011 with the brutal repression of anti-government protests.