The chief Syrian government negotiator at peace talks in Geneva said on Friday he had received a paper from U.N. mediator Staffan de Mistura and would study it, but a first meeting had covered only the format of talks.

Opposing sides in the war came face-to-face at the U.N. for the first time in three years on Thursday, to hear mediator Staffan de Mistura urge them to cooperate.

But with obvious tensions among participants at the opening ceremony and the opposition delegation not fully under one umbrella, there appeared little prospect the sides would meet directly soon.

"During this round of talks we discussed the format of upcoming meetings ... exclusively," Bashar al-Ja'afari told reporters after about two hours of discussions.

"At the end of the meeting de Mistura gave us a paper and we agreed to study this paper. We shall inform him of our position vis-a-vis this paper," he said.

He corrected an interpreter who described it as a "document", and gave no details of what it said. He took no questions.

De Mistura was holding bilateral meetings with the delegations on Friday to establish a plan for this round of negotiations that could run into early March.

At the last Geneva talks, 10 months ago, de Mistura had to shuttle between the parties who never met in the same room. The negotiations made slow progress and were suspended as the war escalated.