Syria's government and opposition will finally hold peace talks on January 22 in Geneva, the UN have said.

Previous attempts to bring the sides together have failed because of disputes over who should represent the Syrian opposition, Syrian President Bashar al-Assad's future role and whether Iran, Saudi Arabia and other regional powers should be at the table.

The UN statement did not specify who will be representing Syria's opposition at the talks, but it is understood that the Syrian National Coalition will participate.

However the group has only limited control over the ragtag army of bitterly divided rebel groups fighting President Assad's forces - and often each other as well.

"The Geneva conference is the vehicle for a peaceful transition that fulfils the legitimate aspirations of all the Syrian people for freedom and dignity and which guarantees safety and protection to all communities in Syria," claimed UN secretary-general Ban Ki Moon's office.

A key goal would be the "the establishment - based on mutual consent - of a transitional governing body with full executive powers, including over military and security entities."

The UN said: "The secretary-general expects that the Syrian representatives will come to Geneva with a clear understanding that this is the objective."

That goal is based on a roadmap adopted by the US, Russia and other major powers, envisaging a transitional governing body with executive powers and leading to elections.

Earlier this month, the Syrian National Coalition agreed to attend peace talks if a number of conditions were met, including humanitarian corridors to give relief agencies access to besieged areas and the release of detainees, particularly women.

But the group maintained that Mr Assad would have no role in the transitional period although it dropped an earlier demand that he step down before talks.

Syrian government officials have been clear that Mr Assad will not step down and may even run for another term in presidential elections.