Former UN Secretary-General Kofi Annan was due in Kenya on Tuesday to mediate a deadly dispute over the country's presidential election, which triggered riots and ethnic fighting that killed more than 600 people. The December 27 election returned President Mwai Kibaki to power for a second five-year term, with official results putting opposition leader Raila Odinga second in the closest presidential race in Kenya's history. But foreign and local election observers have said the vote count was deeply flawed. Although the electoral chief pronounced Kibaki the victor, he later said he had been pressured to do so and did not know who won. Efforts at international mediation so far have failed. Annan was due to arrive late Tuesday to try to bring the two sides together, as US Ambassador Michael Ranneberger urged a political settlement.