International mediator Lakhdar Brahimi has said Syrian government and opposition delegations will meet in the same room tomorrow.

Mr Brahimi was speaking after meeting both sides separately at the UN headquarters in Geneva.

He said both sides accept their talks will be based on a 2012 communique, which called for a transitional governing body to be set up.

"Tomorrow we have agreed that we shall meet in same room. The discussions I had with the two parties were encouraging," Mr Brahimi told a news conference.

"We knew that it was going to be difficult, complicated. We never expected this to be easy. I think the two parties understand what is at stake.

"We do expect some bumps on the road. We wanted these delegations nominated months ago to prepare things better."

He said both delegations would remain in Geneva until at least Sunday.

The talks seemed to falter earlier today when the opposition demanded that the government first endorse the accord calling for a transitional governing body to be established.

Today's meetings came two days after a formal opening conference was held in a poisonous atmosphere, with both sides and their global backers making uncompromising public speeches. 

The opposition says it has come to discuss a transition that will remove President Bashar al-Assad from power. 

The government says it is there only to talk about fighting terrorism - the word it uses for its enemies - and no one can force Mr Assad to go.

Mr Brahimi indicated his aim is to start by seeking practical steps, such as local ceasefires, prisoner releases and access for international aid deliveries, before embarking on the tougher political negotiations.

He told the news conference that they have not yet discussed the "core matters".

Mr Brahimi also said "there are different interpretations on some" of the items from the 2012 accord.

Both sides have agreed to discuss a possible deal to provide humanitarian access to the besieged city of Homs as part of confidence building measures.

Elsewhere, US Secretary of State John Kerry said a political solution was the only way to resolve the crisis.

Speaking at the World Economic Forum in Davos, Mr Kerry reiterated that Mr Assad had no place in the Syria's future.

Syria's civil war has already killed at least 130,000 people, driven up to a third of the country's 22 million people from their homes and made half dependent on aid, including hundreds of thousands cut off by fighting.

Among the hurdles to progress, the Islamist militants who control most rebel-held territory are boycotting the talks and say anyone attending negotiations that fail to bring down Mr Assad would be traitors.

Mr Assad's main regional backer, Iran, is also not represented at the Geneva talks.

UN Secretary-General Ban Ki-moon invited Iran at the last minute, but then withdrew the invitation 24 hours later when it refused to endorse the Geneva 1 protocol.

During Wednesday's opening ceremony, the government delegation drew a rebuke from Mr Ban for using inflammatory language.