The government of war-ravaged Syria on Wednesday welcomed a deal between the presidents of its allies Russia, Iran and rebel backer Turkey to hold a peace "congress" of regime and opposition forces.

"The Syrian government welcomes the closing statement" of the meeting in the Black Sea resort of Sochi, said a foreign ministry source quoted by the official SANA news agency.

Russian President Vladimir Putin said Wednesday that Turkish counterpart Recep Tayyip Erdogan and Iran's President Hassan Rouhani had agreed to the summit, set to place before United Nations-backed talks in Geneva next week.

The congress would "gather representatives of different political parties, internal and external opposition" to discuss "the parameters of the future state," he said.

The Syrian foreign ministry official said Syria has "always" supported "any political action that respects its sovereignty, independence and territorial integrity, and helps put an end to the shedding of Syrian blood".

Numerous attempts to end the war in Syria have failed.

A major stumbling block is the fate of President Bashar al-Assad, whose opponents demand his immediate departure.

A new round of United Nations-backed talks is set for November 28 in Geneva.

Anti-government protests broke out in Syria in 2011.

The government's brutal response sparked a complex civil war that has wracked swathes of the country, killed more than 330,000 and displaced millions.