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NAIROBI, April 13 (Reuters) - Kenyan President Mwai Kibaki will unveil a long-awaited coalition cabinet on Sunday after secret discussions with opposition leader Raila Odinga ended a six-week impasse, Kibaki's office said.

"A breakthrough was made in the talks and President Kibaki and Hon. Raila agreed to the announcement of the cabinet today," it said in a statement, adding that this would be done at State House in Nairobi at 4 p.m. (1300 GMT).

The appointment of a power-sharing cabinet is central to a deal to end the east African country's post-election crisis. More than 1,200 people were killed and 300,000 uprooted in the country's worst violence since independence in 1963.

Political sources who disclosed the agreement late on Friday gave no immediate details about the make-up or size of the cabinet, or whether either side had given up claims to influential ministries.

Odinga's Orange Democratic Movement has not commented publicly on the apparent breakthrough.

Kibaki, 76, and Odinga, 63, met on Saturday at Sagana State Lodge, a fishing retreat 100 km (60 miles) northeast of Nairobi, which was a wedding gift to Queen Elizabeth before she ascended the throne. Britain returned it to Kenya at independence.

The two leaders agreed to appoint a 40-member cabinet on April 6, but the deal fell apart at the last minute, unsettling Kenyans and investors fearful of a return to violence.

The two men have come under local and international pressure to break the deadlock on the cabinet, part of a peace deal brokered in February by former U.N. Secretary-General Kofi Annan.

In the week since the first cabinet deal fell through, Kibaki and Odinga have urged calm and said their positions were not far apart.

Violence erupted after Odinga accused Kibaki, Kenya's longest-serving politician, of rigging his re-election in the Dec. 27 vote, Kenya's closest presidential poll.

The electoral fight degenerated into ethnic killings and riots that shattered Kenya's image as a stable tourism and trade hub, with one of sub-Saharan Africa's most promising economies. (Writing by Daniel Wallis; editing by Andrew Dobbie) (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/ ) (For a timeline since the election, click on [nL12856367])

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