Failure of the main Syrian National Coalition to take a clear stance over the talks, which aim to find a political solution to Syria's 2-1/2 year civil war, are also expected to contribute to a delay of up to one month, the officials said on Wednesday.

"A clearer picture will emerge when the United States and Russia meet next week, but all indications show that the November 23 goal will be difficult to meet," said one of the officials involved in preparing for the talks.

US, Russian and UN envoys are due to meet in Geneva next Tuesday as part of the preparation for the long-delayed peace conference, which was first proposed back in May.

A main point of contention, the official said, is the role of the Western-backed opposition coalition - an issue which has flared up since a meeting in London last week of Western and Persian Gulf Arab countries opposed to the Syrian government.

They announced that the Geneva negotiations should be between a "single delegation of the Syrian government and a single delegation of the opposition, of which the Syrian National Coalition should be the heart and lead."

Russia sees the coalition as just one part of the opposition and has suggested that several delegations, including Damascus-based figures tolerated by the government, could represent the Syrian government’s foes.

That position was echoed by Hassan Abdul Azim, head of the opposition National Coordination Body, who said after meeting international peace envoy Lakhdar Brahimi in Damascus that delegates should attend not under the banner of the coalition but as part of a united "Syrian National Opposition".

A communiqué at the end of the London meeting also said Geneva would aim to establish a transitional government by which time President "Assad and his close associates will have no role in Syria".

"The Russians are furious at the strong stance taken in London and that the communiqué went a long way towards satisfying the demands of the coalition," a Western official said.

NTJ/NJF