TEHRAN (Press Shia Agency) – Some 1,600 people have been invited to the Russian Black Sea resort of Sochi next week for a Syria peace congress with the aim of agreeing a post-war constitution, Moscow said Thursday.

"Invitations have been sent and continue to be sent to Syrian participants, some 1,600 people will receive such invitations," Russian foreign ministry spokeswoman Maria Zakharova said of the Sochi negotiations, AFP reported.

International observers, including those from the UN, will take part in the Congress along with Syrian parties, Zakharova said in comments reported by Russian news agencies.

Russia's Foreign Minister Sergei Lavrov will also attend.

Syria's main opposition group, the Syrian Negotiations Commission, this week said it would need further details before it could make a final decision on whether to attend the talks, which dozens of rebel factions have already rejected.

The Sochi meeting, scheduled to be held on January 30, is part of a broader push by Moscow, Tehran and Ankara to start hammering out a path to a political solution to end the conflict.

Moscow initially hoped to convene peace talks in Sochi last November but those efforts collapsed following a lack of agreement among co-sponsors.

Separate UN-backed talks began in Vienna on Thursday, to continue until Friday.