US Secretary of State John Kerry said Thursday peace talks to solve the crisis in Syria would proceed on January 25 as planned, despite a dispute over who would represent the country's opposition.

"It may be a day or two for invitations but there is not going to be a fundamental delay. The process will begin on the 25th and they will get together and see where we are," Kerry said on the sidelines of meetings at the World Economic Forum in Davos, Switzerland.

The latest bid to end the Syrian war through indirect talks between the government and opposition will take place in Geneva.

But a disagreement over which parts of the opposition will be present at the negotiations, and who will represent them, is posing new obstacles.

On Wednesday, the main coalition of opposition bodies, the so-called High Negotiations Committee, announced its own delegation to the talks.

But its decision to name a member of the Jaish al-Islam rebel group as its chief negotiator has drawn criticism both from some of its own members, and opposition figures excluded from the coalition.

The National Coordinating Committee for Democratic Change, a key opposition body still present in Damascus, said the choice was "not acceptable".

And Haytham Manna, an opposition figure who does not belong to the High Negotiations Committee, accused it of including "war criminals" in its delegation.

Damascus's delegation will be headed by the Syrian ambassador to the United Nations, Bashar al-Jaafari, and overseen by Deputy Foreign Minister Faisal al-Moqdad, the Syrian government source has said.