Talks aimed at ending the political crisis in Kenya have stalled, forcing mediator Kofi Annan to intervene.

He is to seek the input of President Mwai Kibaki and rival Raila Odinga in an attempt to salvage the process.

Negotiators from Mr Odinga's Orange Democratic Movement and the government disagree on the powers to be granted to a proposed new post of prime minister.

Police have increased their estimate of the death toll of post-election clashes and now say at least 1,500 have died.

Another 300,000 others were displaced in the violence following the 27 December poll.

The opposition ODM has threatened to relaunch mass protests on Thursday if a political deal is not reached, while a lawyers' group says it wants to see a resolution by the end of the week.

Leverage

Mr Odinga, who insists victory was stolen from him, arrived at the venue of talks and left after a brief meeting with Mr Annan.

"We have isolated a number of issues which now require our chairman to consult with the principals," Mutula Kilonzo, a representative of the government, told reporters.

Both parties walked away from the venue of the talks after new proposals were raised, sources told the BBC.

"On many of the issues that are outstanding, we are unable to agree, so they have been referred to the principals in the hope that they enjoy greater leverage and can be able to thrash out those issues," said William Ruto, of the ODM.

Power-sharing

The ODM and government negotiators were due to fine-tune an agreement that would usher in a new power-sharing arrangement.

The incoming African Union commission chairman, Jean Ping, who held talks with President Kibaki and Mr Annan, hinted last week that a deal would be announced early this week.

Both parties have agreed in principle on the creation of a prime minister's position, which would be taken by Mr Odinga.

As well as how to divide powers between a prime minister and a president, they are also split on sharing on cabinet positions and the possibility of a new election if the coalition collapses.

Impatient

Pressure is mounting on both Mr Kibaki's Party of National Unity (PNU) and the ODM to agree to a power-sharing settlement that would end the political crisis.

"We share the impatience on the expectations of the outcome of the Annan-led talks. We would like to see a consensus reached between the two parties by the end of the week," said Tom Ojienda, president of the influential East African Law Society.

But some pro-government leaders have cautioned the government against rushing for a quick-fix deal, with some pushing for the final agreement to be put to a referendum for public endorsement.