US Republican Senator John McCain has conceded Russia is a key player in the Syrian peace process after it invited the United States to talks in Astana, in an interview with MSNBC.

Russia, Turkey and Iran brokered the Astana talks and agreed to act as guarantors of a nationwide Syrian ceasefire.

The negotiations between the Syrian government and opposition will be held on January 23 in the run-up to a Geneva meeting in February.

"He [President Vladimir Putin] is now a major player in the Middle East. There’s nothing more significant than the Russians, the Iranians and the Turks inviting the US to come to a peace conference," McCain told the news channel on Tuesday.

The Arizona lawmaker, who has been Russia’s vocal critic throughout his career, regretted the United States was not leading the new effort to relaunch intra-Syrian talks that will get underway next week in Kazakhstan’s capital Astana.

"The US isn’t leading, the US isn’t even part of it but they’re ‘being invited.’ How far we have come," he concluded.