Mistura said the process of finalizing the list of participants “is still ongoing,” particularly regarding clarification of the opposition groups which will not be considered “terrorist.”

He added that the UN will start sending invitations on Tuesday. “I’m going to send the invitations given by the mandate of the UN Security Council,” he said.

The #SyriaTalks are to begin in Geneva on Friday 29 January, says UN Special Envoy for Syria Staffan de Mistura.

The peace talks were originally due to start on Monday, but were postponed.

"We want to make sure that when and if we start, to start at least on the right foot. It will be uphill anyway," Mistura said.

He added that the “proximity talks” between the two sides are expected to last six months. According to the UN official, “this will not be Geneva-3.”

Mistura told reporters that the sides will not talk directly to each other and will be mediated by negotiators.

The first part of the talks will last from two to three weeks, the envoy said, adding that the focus will be on negotiating a ceasefire, stopping Islamic State and increasing humanitarian aid. Among the priorities will also be the issues of governance, a constitutional review and future UN-backed election.