Negotiations between Kenya's government and the opposition have been suspended.  As Derek Kilner reports from Nairobi, the two sides have been unable to agree on the terms of a power-sharing arrangement to break the political deadlock gripping the country since a disputed presidential election in late December.

The chief mediator for the talks, former U.N. Secretary-General Kofi Annan, plans to consult with President Mwai Kibaki and opposition leader Raila Odinga on how to move the negotiations forward.

President Kibaki's Party of National Unity has agreed to the creation of a prime minister's office that would be filled by the opposition Orange Democratic Movement, better known as ODM. 

But the two sides have not agreed on how much power a prime minister would have. Nor is there agreement on what level of representation the ODM should have in the cabinet, or on whether new elections should be held if the coalition collapses.

Speaking after the negotiations adjourned, opposition negotiator Musalia Mudavadi criticized the government.

"We have been extremely frustrated as ODM, because there are moments we believe we have made ground and we realize the following day there is actually a reversal," Mudavadi said. "We as ODM ceded substantial positions.  The other side is coming from a premise that the constitution cannot be touched."

Both sides have agreed to a long-term constitutional review, once a political settlement is reached, but the opposition wants some constitutional amendments now to support a power sharing arrangement.  

Government negotiator Mutula Kilonzo said his side is feeling unduly pressured in the talks.

"We are not going around in circles," Kilonzo said. "It is just that we have firm positions on both sides.  And the atmosphere for bridging the gap between the two of us is not fair.  As I say, we have tended to feel that we are being railroaded."

U.S. Secretary of State Condoleezza Rice, who visited Kenya last week, issued a statement saying she is "disappointed by the failure of leadership" in the negotiations, reiterating U.S. support for a political solution.

Tanzanian President Jakaya Kikwete, who currently heads the African Union, is to arrive in Kenya late Tuesday to contribute to the mediation effort.    

The opposition has notified the police of plans for widespread demonstrations on Thursday if no progress is made on the talks.  Mudavadi refused to discuss the protest call.

The government has criticized the proposed demonstrations.  While the opposition has said any action will be peaceful, other protests since the elections have led to looting and provoked violent responses from the police.

Police also said they have arrested around 200 youths who were said to be engaged in military training in Kenya's west.

Last week, the International Crisis Group, a research organization based in Brussels, warned of the ongoing mobilization of armed groups in the country supporting both the government and opposition.  

The authorities say 1,500 people have been killed in violence following December's presidential elections, which the opposition charges were rigged.  The country has returned to relative calm in recent weeks.