(Adds finance minister, paragraph 11, credit rating 15-16)
By C. Bryson Hull and Andrew Cawthorne
NAIROBI, Jan 2 President Mwai Kibaki's government accused rival Raila Odinga's party of unleashing "genocide" in Kenya on Wednesday as the death toll from tribal violence over a disputed election passed 300.
"It is becoming clear that these well-organised acts of genocide and ethnic cleansing were well planned, financed and rehearsed by Orange Democratic Movement leaders prior to the general elections," said the statement read by Lands Minister Kivutha Kibwana on behalf of his colleagues.
Odinga's party shot back that the government was also "bordering on genocide" by ordering police to shoot protesters enraged by Kibaki's victory in the Dec. 27 polls that international observers said fell short of democratic standards.
Both sides alleged massive rigging.
Kenya is an important ally of the West in its counter-terrorism efforts, takes growing money flows from China, and is used to being the peacemaker in African hot-spots like Somalia and Sudan rather than the problem.
Kibaki's Kikuyu tribe was targeted in the initial violence, but revenge killings by Kikuyus are on the rise in mayhem that rights groups say has been exacerbated by a police crackdown on rioting and looting.
Apparently offering an olive branch to the ODM, which draws most of its support from western Kenya's Luo tribe, Kibaki invited all members of the new opposition-dominated parliament to a meeting at State House in Nairobi.
But no opposition MPs attended as Odinga demanded outside mediation: "We cannot dialogue with a thief," he told reporters. "We are not interested in talking with Kibaki without international mediation."
A statement by Kibaki's office deplored the violence and vowed to secure roads "so essential goods and services can reach people in the areas and other countries in the region".
CREDIT RATING HIT
Ghanaian President and African Union Chairman John Kufuor has been urged by the West to mediate and was waiting to talk to Kibaki before deciding whether to go himself or send a team.
British Prime Minister Gordon Brown said Kufuor would fly to meet Kibaki and Odinga on Thursday. Late on Wednesday, Finance Minister Amos Kimunya told BBC Radio there was no need for Ghana's president to come.
Odinga plans a mass rally on Thursday that the government has banned on security grounds.
The use of the word genocide will horrify Kenyans, used to being viewed by the world as a stable democracy, an investment and tourist destination and oasis of peace in a volatile region.
The turmoil delayed trading in the shilling currency, which then dropped to a six-week low. Stocks also fell and tea and coffee auctions were postponed.
Standard & Poor's cut Kenya's long-term local currency credit rating to 'B+' from 'BB-' and said if the violence was not resolved, the foreign currency credit rating could be lowered as well. It put both the long-term foreign and local currency ratings on "CreditWatch with negative implications".
Kenya's foreign currency credit rating is 'A', well into investment grade territory. It is on par with Moody's Investors Service, which gives it an 'A2' rating while Fitch Ratings has the country one notch higher at 'A+'.
"MORE THAN 300 DEAD"
More than 300 people have died in an explosion of tribal violence since Kibaki's disputed re-election on Sunday.
British Foreign Minister David Miliband and U.S. Secretary of State Condoleezza Rice called for an end to violence and "an intensive political and legal process" to end the crisis.
As young men armed with machetes manned roadblocks in rural areas, a trickle of office workers in the capital Nairobi made it through police cordons to begin the new working year.
A local and an international rights group gave a death toll of "more than 300" and accused Kenyan security forces of having "bloodily repressed" protests by opposition supporters.
"As a reaction, some protesters are responsible for the assassination of Kikuyus,"added the Kenya Human Rights Commission and the International Federation for Human Rights.
On Tuesday, about 30 Kikuyus died when a mob set fire to the church where they had taken sanctuary in the western town of Eldoret. It was one the worst outbursts of violence that has uprooted nearly 100,000 Kenyans, some fleeing to Uganda.
There were growing examples on Wednesday of revenge killings by Kikuyu militants. In Naivasha town in the Rift Valley, scores of people were injured in retaliation for the church killings.
The Kikuyu have dominated political and business life in east Africa's biggest and fastest-growing economy since independence from Britain in 1963.
Adding to the chaos, Kenya's electoral commission head Samuel Kivuitu said: "I do not know" when asked if Kibaki won.
Kivuitu pronounced Kibaki the victor on Sunday, and his remark stunned Kenya and cast further doubt on the result. (Additional reporting by Nicolo Gnecchi, Helen Nyambura-Mwaura, Katie Nguyen, George Obulutsa, Daniel Wallis, Antony Gitonga, Bryson Hull; Jeremy Lovell in London; Daniel Bases in New York; editing by Tim Pearce)