(Adds government reaction to Rice's statement, Michel)

By Giles Elgood and Daniel Wallis

NAIROBI, Feb 26 (Reuters) - U.S. Secretary of State Condoleezza Rice criticised Kenyan leaders on Tuesday for failing to end their political stand-off and said Washington would take "necessary steps" unless a solution was reached.

Government and opposition negotiators failed to reach a breakthrough on a power-sharing deal, prompting mediator Kofi Annan to suspend the talks while he consulted President Mwai Kibaki and opposition leader Raila Odinga.

"The talks have not broken down," Annan told reporters. "But I am taking steps to make sure we accelerate the process and give peace to the people as soon as possible."

Rice, who is on a trip to China, said that while there had been some progress, "I am disappointed by the failure of leadership necessary to resolve all the remaining issues."

She added: "I want to emphasise that the future of our relationship with both sides and their legitimacy hinges on their cooperation to achieve this political solution.

"In that regard, we are exploring a wide range of possible actions. We will draw our own conclusions about who is responsible for lack of progress and take necessary steps."

She did not elaborate.

Rice, who visited Kenya earlier this month to urge progress, said the United States would also "exercise leadership" to press for a political solution through the United Nations, the African Union and the European Union.

Kibaki and Odinga have come under international and domestic pressure to compromise over Kibaki's disputed re-election in a Dec. 27 vote, an event that triggered ethnic violence in which 1,000 people were killed and 300,000 forced to flee their homes.

"REWARD VIOLENCE"

Foreign Minister Moses Wetangula, who is a member of the government negotiating team, rejected Rice's criticism. "Our international friends ... are welcome to make suggestions to support the dialogue process, but not impose solutions and should take care not to legitimise or reward violence, death and destruction," he told a news conference.

"All factors must be taken into account to avoid making rush judgements based on incomplete information. We wish to reassure Kenyans that the government is fully committed to the dialogue process and to finding a lasting solution."

Adding his weight to efforts to forge a deal, Tanzanian President Jakaya Kikwete arrived in Kenya in his capacity as African Union chairman to talk to Kibaki, Annan and Odinga.

Mediator Annan, the former U.N. secretary-general, is frustrated and ready to leave the country Kenya if there is no progress soon, according to a source close to the talks.

In Brussels, the European Union aid chief Louis Michel expressed "utmost concern" that the talks had stalled.

"The country clearly stands at the crossroads," Michel said.

The opposition has said it will stage nationwide protests beginning on Thursday if there is no deal. Police had no comment on whether they would permit the demonstrations.

Musalia Mudavadi, a senior opposition leader, refused to rule the protests out after the talks were suspended.

"That will be a subject for another day," he told reporters.

Earlier protests descended into riots and looting that were met with a deadly police response, and rounds of ethnic killings and revenge attacks erupted in different parts of the east African country.

The bloodshed damaged Kenya's reputation as a prosperous trade and tourism hub in a volatile region. Against this background of violence, the government has agreed in principle to create a prime minister's seat demanded by the opposition.

But the parties are split on the premier's powers, the sharing of ministries and the possibility of a new election if the coalition collapses. (Additional reporting by Duncan Miriri; editing by Daniel Wallis and Andrew Roche) (For in depth coverage on Reuters Africa Web site: http://africa.reuters.com/elections/kenya/ )

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