UN special envoy for Syria, Geir Pederson, arrived in Damascus Tuesday to try and secure a constitutional committee to revive a peace process which never really was.

"Pleased to be back in Damascus," Geir Pederson, wrote on Twitter.

His visit is the fourth since taking up the job in January and comes as the Damascus regime and their Russian ally are hitting the region of Idlib where jihadists have moved.

In his tweet, Pederson said: "Hopeful we can move the political process forward with the constitutional committee as a door opener, and that we can find a way to end the violence in Idlib."

The regime wants to amend the existing constitution, while the opposition have called for a new one entirely.

The committee is to be made up of 150 members, 50 chosen by the regime, the same number by the opposition, and another 50 selected by the UN envoy.