Syria's main opposition group said Monday it needed "full and clear information" from Russia before it would agree to take part in peace talks to be held in Sochi next week.

The comments came during a visit by the Syrian Negotiations Commission (SNC) to Moscow as Russia gets set to host talks in the Black Sea resort on January 30 along with Syrian regime-backer Iran and rebel-supporter Turkey.

"The SNC will not make any final decision regarding the Russian initiatives until it receives full and clear information from Russia," SNC representative Nasr al-Hariri said at the start of a meeting with Russian Foreign Minister Sergei Lavrov.

"We want to have complete information about the participants, the agenda and the objectives" of the Sochi meetings, he said in comments translated into Russian.

"Unfortunately, for the time being, we do not have a clear picture of all that."

The SNC has said it will attend fresh UN-hosted negotiations before the Sochi talks, which dozens of rebel factions have already rejected.

Lavrov said he was looking forward to a "constructive conversation" with Hariri.

"We consider counterproductive the attempts of some foreign players to question the sincerity of the efforts we are undertaking," Lavrov said.

Numerous rounds of UN-brokered peace talks have been held in Geneva, with the last one concluding in mid-December with no notable progress towards ending the country's war.

The UN-backed talks are to resume on January 25-26, this time in Vienna.

Key players Russia, Iran and Turkey have been sponsoring parallel peace talks since the start of last year.

The Sochi meeting is part of a broader push by Moscow to start hammering out a path to a political solution to end the war and has sparked concerns that the Kremlin is looking to sideline the UN.

The Damascus government has said it would attend the Sochi talks, which are aimed at setting up a new constitution for post-war Syria.

Syria's nearly seven-year war, which began as the regime brutally crushed anti-government protests, has claimed more than 340,000 lives, forced millions to flee their homes and left the country in ruins.