BEIRUT (Reuters) - Turkey-allied Syrian rebels said on Saturday they would cooperate with Turkish diplomatic efforts that have halted a Russian-backed government offensive in Idlib, but they will not surrender their weapons or territory.

Turkey and Russia struck a deal on Monday that will create a demilitarized zone between government and rebel fighters in northwestern Syria, sparing the area a major offensive for which pro-government forces had been mobilizing.

Under the agreement, “radical” insurgents must withdraw from the zone by Oct. 15. Russian President Vladimir Putin has said the zone will be 15 to 20 km (10 to 12 miles) deep and run along the contact line between rebel and government fighters.

It will be patrolled by Turkish and Russian forces.

The National Front for Liberation, which groups a number of Free Syrian Army factions deemed moderate by Turkey, announced “our complete cooperation with the Turkish ally in making their effort succeed in sparing civilians the calamities of war”.

In a statement, it added “we remain cautious and alert to any treachery by the Russians, the regime and the Iranians, especially after the issuance of statements by them that indicate this agreement is temporary”.

“Our finger will remain on the trigger and we will not forgo our weapons or our land or our revolution,” it said.

Putin has said that all opposition heavy weapons, mortars, tanks, rocket systems are to be removed from the demilitarized zone by Oct. 10.

Turkey has said the “moderate opposition” would keep its weapons and remain in the areas it holds, and the “region will be cleared of radicals”.

The most powerful jihadist group in the northwest, Tahrir al-Sham, has yet to declare its position on the Turkish-Russian agreement. Tahrir al-Sham is an amalgamation of jihadists dominated by the group formerly known as the Nusra Front, which was an official affiliate of al Qaeda until 2016.

Close to 3 million people live in Idlib, around half of them Syrians displaced by the war from other parts of Syria, and the United Nations warned that an offensive would cause a humanitarian catastrophe.