Naji al-Mustafa, spokesman for the National Front for Liberation, a Turkish-backed umbrella group, said Sunday the alliance had unanimously agreed to implement the deal reached last month and expected to demilitarize 15-20 kilometres along the front lines by Oct. 15.

He said opposition forces would keep forward bases and light and medium weapons in place.

The Britain-based Syrian Observatory for Human Rights reported Monday that nearly all heavy weapons have been removed from the area on the southern edge of Idlib.

WATCH BELOW: Syria and Russia pound rebel stronghold in Idlib

The Observatory’s chief, Rami Abdurrahman, said that even al Qaeda-linked militants and other jihadis are withdrawing their heavy weapons, hoping to avoid a confrontation with Turkish troops and allied Syrian fighters.

The al Qaeda-linked Levant Liberation Committee, the largest armed group in Idlib, has not said whether it will comply with the deal.