Turkish President Tayyip Erdogan and his Russian counterpart Vladimir Putin have agreed that a working group on Syria’s northwest should convene as soon as possible, Turkey’s foreign minister said on Wednesday.

A recent offensive targeting Syria’s Idlib and surrounding areas by the Syrian army and its allies, backed by Russia, has uprooted more than 150,000 people, the United Nations says, while rescue workers and civil defense officials say more than 120 civilians have been killed.

Foreign Minister Mevlut Cavusoglu said that attacks by Syrian government forces were damaging prospects of forming an UN-sponsored committee to draft a new Syrian constitution.