UN special envoy to Syria Geir Pedersen underlined on Monday the need to implement Security Council resolution 2254 to ensure the safe return of refugees to their homes.
He made his remarks in Moscow where he met Russian Foreign Minister Sergei Lavrov.
He voiced his determination to work with Russia to set the political settlement on Syria back on track.
The UN and Russia must play a central role in Syria and ensure the success of the political process, said Pedersen.
Relations between Moscow and the UN must also be developed, he added.
Pedersen had kicked off his duties last week by holding talks with Syrian officials in Damascus.
He is the fourth UN envoy to seek a solution to Syria's conflict, after endless rounds of failed UN-brokered peace talks.
