A Syrian government delegation is due to meet officials in Moscow on Monday to discuss an international peace conference that Russia, the U.S. and the United Nations are trying to convene, a Russian diplomatic source said.
Russia and the U.S. announced in May that they would try to organize a conference to bring Syria's government and opposition together for talks. No date has been set but diplomatic efforts to hold the talks have intensified in recent weeks.
The Syrian delegation may meet Foreign Minister Sergei Lavrov on Tuesday, the source said.
In a conversation on Friday with UN special envoy Lakhdar Brahimi, Lavrov voiced hope that a preparatory meeting between Brahimi, U.S. and Russian diplomats on Nov. 25 would "resolve all remaining questions" including which other nations would take part in the conference, the Russian Foreign Ministry said.
Global powers have disagreed over whether Iran, Assad's main regional backer, should be invited.
The opposition Syrian National Coalition agreed Monday to attend the conference but said there could be no role for President Bashar Assad in Syria's future.
Russia says Assad's exit from power cannot be a precondition for the talks aimed at ending the civil war, which has killed more than 100,000 people.
Syrian National Coalition Secretary General Badr Jamous said Friday that the opposition coalition was considering an invitation to visit Moscow next week, RIA Novosti reported.
The Russian Foreign Ministry declined to comment on what would be the first known visit by the coalition.
Russia has been the Syrian government's most powerful backer during the conflict, sending arms and blocking Western efforts to condemn or pressure Assad.
President Vladimir Putin praised Assad's readiness to send a delegation to the conference when he spoke to the Syrian leader by telephone Thursday in what Putin's spokesman said was their first conversation in at least two years.
Putin has said in the past that Russia has no special relationship with Syria, which buys arms from Moscow and hosts its only naval base outside the former Soviet Union, but has also said Assad's exit could leave a dangerous political vacuum.