BEIRUT (Reuters) - A jihadist faction in the Idlib region of northwestern Syria has rejected a Turkish-Russian deal that requires “radical” insurgents to withdraw from a demilitarized zone, and urged rebels to launch new military operations.

FILE PHOTO: A member of Nusra Front climbs a pole where a Nusra flag waves in the town of Ariha in Syria's Idlib province, May 29, 2015. REUTERS/Khalil Ashawi/File Photo

While the Huras al-Din faction is not the main Islamist militant group in Idlib, its statement points to objections that may complicate the implementation of the agreement clinched last week by Russia and Turkey.

The most powerful jihadist group in the northwest, Tahrir al-Sham, has yet to declare its stance on the deal, under which insurgents must vacate the demilitarized zone by Oct. 15.

Tahrir al-Sham is a coalition of Islamist groups dominated by the faction formerly known as the Nusra Front, which was an official wing of the al Qaeda network until 2016. Tahrir al-Sham’s position will be critical.

An alliance of Turkey-allied rebel groups, the National Front for Liberation, has declared its “complete cooperation” with the Turkish effort, but has also ruled out disarming or yielding territory.

The Huras al-Din group was formed earlier this year by combatants who split from Tahrir al-Sham and the Nusra Front when it cut its ties with al Qaeda. It includes foreign militants.

The group declared the agreement part of a plan “to eliminate the jihadist project” in the Levant.

“We advise our mujahideen brothers in this decisive and dangerous phase ... (to) begin military operations against the enemies of religion to thwart their plans,” it said in a statement released on Saturday.

The demilitarized zone agreed by Turkey and Russia 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.

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

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 has warned that an offensive would cause a humanitarian catastrophe.