Moscow, Washington and the United Nations will hold talks on Syria in Geneva on Friday ratcheting up diplomatic efforts to end the conflict, Russia said on Wednesday.
"We will be having consultations in the trilateral format - Russia, the United States and the UN," deputy foreign minister Gennady Gatilov told state news agency RIA Novosti.
UN peace envoy Staffan de Mistura is set to take part in the talks aimed at ending a brutal war that has killed more than 250,000 people and forced millions from their homes since March 2011.
"We are meeting this time first of all to hear Mr de Mistura speak about the UN`s work and the modalities of progress in the inter-Syrian dialogue," Gatilov said.
Gatilov said Russia would be calling for the "intensification of joint efforts" in the "fight against terrorism".
He underlined the importance of coming up with a "list of terrorist organisations" as well as "a list of the opposition members who could take part in the negotiation process".
Representatives from Syria's fragmented opposition on Wednesday began a two-day closed-door meeting in Saudi Arabia to seek a united front for potential talks with Syrian President Bashar al-Assad.
The meeting represents for the first time a broad range of Syrian political and armed opposition factions have come together since the conflict erupted.
Diplomats from 17 countries have held two meetings in Vienna since October to agree on a roadmap to end the war.
US Secretary of State John Kerry said he would visit Moscow next week as Russia and the US work to forge a framework for a Syrian ceasefire and political transition.
Moscow has sought, so far without success, to persuade nations in the US-led coalition that opposes Assad to work with its own forces flying a bombing campaign in Syria and with Damascus in a broader coalition against the Islamic State (IS) jihadist group.