An international peace conference aimed at ending Syria's civil war will be held on 22 January, the United Nations has said.

It will be the first face-to-face meeting between the government of Syrian President Bashar al-Assad and rebels seeking to overthrow him.

The UN is hoping for a peaceful transition in Syria, building on an agreement between world powers reached in June last year.

The deal calls for the warring sides to set up a transitional governing body with full executive powers, including over military and security entities, but leaves open the fate of Mr Assad.

"We will go to Geneva with a mission of hope," UN Secretary-General Ban Ki-moon said in a statement.

The announcement came as Syria mediator Lakhdar Brahimi met senior US and Russian officials in Geneva.

It is his latest effort to get negotiations on track to end a war that has killed more than 100,000 people.

Mr Brahimi, with backing from world powers, has been trying to convene a peace conference since May and had hoped it could be held in December.

The participation of Syria's ally Iran in the peace conference has been a major stumbling block as the US has opposed it, while Russia and Mr Brahimi have backed Iran's attendance.

It was not clear from Mr Ban's statement whether Iran would be invited to the "Geneva 2" talks.

He said he expected "all regional and international partners to demonstrate their meaningful support for constructive negotiations".