NAIROBI, Kenya (AP):

Kenya's president and his chief rival made key concessions yesterday to end the dispute over the country's elections, calling off protests and agreeing to talks under pressure from the United States as the death toll from a week of violence reached nearly 500.

The top American envoy to Africa says the vote count at the heart of the dispute was tampered with and both sides could have been involved.

The December 27 election returned President Mwai Kibaki to power for another five-year term, with his rabble-rousing opponent, Raila Odinga, coming in second after his early lead evaporated overnight.

"Yes, there was rigging," the U.S. envoy, Jendayi Frazer, told The Associated Press in an interview in Nairobi, where she has been meeting with Kibaki and Odinga for the past three days. "I mean there were problems with the vote counting process. Both the parties could have rigged.''

She said she did not want to blame either Kibaki or Odinga.

Kenya's electoral commission chairman Samuel Kivuiti has himself said he is not sure Kibaki won, though the chairman officially declared Kibaki the winner in the closest presidential election in Kenya's history.

The U.S. intervention appears to be having an effect on the crisis, with both sides softening their tones since Frazer's arrival. Kenya is crucial to the United States' war on terrorism.

Kenya has turned over dozens of people to the U.S. and Ethiopia as suspected terrorists, allows American forces to operate from Kenyan bases and conducts joint exercises with U.S. troops in the region. The U.S. is also a major donor to Kenya, long seen as a stable democracy in a region that includes war-ravaged Somalia and Sudan. Aid amounts to roughly US$1 billion a year, said embassy spokesman, T.J. Dowling.