GENEVA, Sept. 4 (Xinhua) -- UN Special Envoy for Syria Staffan de Mistura on Tuesday appealed to prevent a bloody conflict in the northern Syrian area of Idlib, saying that next days would be "critical".

"Let's try to avoid that the last probably major battle of this Syrian territory conflict ends in talks and not in a bloodbath," he said.

According to the UN Envoy, there are currently 2.9 million civilians in Idlib among whom 10,000 fighters from al Nusra are mingling and which the UN Security Council has declared as a terrorist organization.

Saying that the UN priority is the protection of civilians avoiding a military confrontation, de Mistura told a press conference here Tuesday that "Idlib is our first priority and Idlib is our second priority because we are very concerned".

He also noted that on Tuesday there were six air strikes on Idlib which was concerning.

Earlier Tuesday, de Mistura announced a new UN-led effort to move forward the process to end the Syrian conflict, saying senior officials from Russia, Turkey and Iran will meet in Geneva next week for constitution-related discussions.