(Adds Annan)

By Duncan Miriri and Daniel Wallis

NAIROBI, Feb 22 (Reuters) - Negotiators for Kenya's political rivals broke off talks on the post-election crisis for the weekend on Friday despite growing local and international calls for a quick deal.

With negotiations now hinging on the details of a new prime minister's post to be offered to opposition leader Raila Odinga in a power-sharing agreement with President Mwai Kibaki, the two sides said they would resume on Monday.

"While we made some progress today ... the parties felt there were still some issues on which they needed to consult their principals," said disappointed mediator Kofi Annan.

The former U.N. boss urged Kibaki and Odinga to make decisions and communicate them to negotiators so that a settlement can be urgently reached when talks re-start.

"Many thought the white smoke would emerge from our discussions today," said Annan, who has become a celebrity in Kenya for his efforts to end the post-election crisis that has killed 1,000 people and made more than 300,000 homeless.

"We must give the Kenyan people what they are hoping and praying for. They have suffered greatly."

Adding to the diplomatic pressure, Africa's top diplomat Jean Ping spent Friday in Kenya to back the mediation.

The government agreed in principle this week to create the premier's post, but the sticking point is how much power that position will command. Local media, civil groups, business leaders and clerics have all been pleading for a settlement.

"We hope that next week we'll have something which can be agreed," Ping, the newly elected African Union Commission chairman, told reporters.

PROTEST THREAT

The opposition wants a powerful role as executive premier for Odinga, who accuses Kibaki of rigging the Dec. 27 poll.

Kibaki's team says he won fairly and accuses the opposition of instigating riots and ethnic violence that wrecked Kenya's image as a stable business, tourism and transport hub.

Odinga's Orange Democratic Movement (ODM) has withdrawn an earlier call for Kibaki to resign, but is threatening to resume street protests if its demands are not met.

"If by Wednesday ... no tangible outcome is achieved from the mediation process, party members are hereby called upon to prepare for immediate mass civil disobedience," ODM member of parliament Ababu Namwamba told a news conference.

The government has predicted a settlement in days.

Pressure has grown on both sides of the political divide to reach a lasting deal to end turmoil that has horrified locals, neighbouring states and world powers alike.

"The most effective way to get these issues solved is for the leaders to feel pressure from their own people," U.S. President George W. Bush said on his way home from an Africa tour where the crisis was on high on the agenda.

"We'll help. We send people over and we'll stay engaged."

Odinga left Kenya on Friday on a private trip to Nigeria, but that was not expected to have a bearing on the talks. He told local radio there he was just visiting friends.

Although the east African nation has been relatively calm for two weeks, the ODM protests ultimatum has stoked fears of a resumption of the post-election bloodshed.

Earlier demonstrations often descended into looting and tribal attacks, and were met with a tough police response.

The crisis has laid bare issues of land, ethnicity, wealth and power that have plagued Kenya since British colonial rule, and have often been exploited by politicians since then. (Additional reporting by Helen Nyambura-Mwaura and Wangui Kanina, Editing by Andrew Cawthorne) (For special coverage from Reuters on Kenya's crisis see:

http://africa.reuters.com/elections/kenya/)

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