People inspect the damage at a site hit by airstrikes in the rebel-held city of Idlib, Syria on February 7, 2017. Photo: REUTERS/Ammar Abdullah.

The Syrian Observatory for Human Rights said on Sunday that rebel group Failaq al-Sham has started withdrawing its forces and heavy arms from a demilitarized zone in northwest Syria.

The group is the first to comply with a requirement to leave a demilitarized buffer zone set up by Turkey and Russia to avert a Russian-backed Syrian army offensive, Rami Abdulrahman, head of the UK-based war monitor told Reuters.

Rebel sources could not immediately be reached for comment.