NAIROBI, Kenya - Kenya's president and his chief rival held talks Thursday for the first time since last month's disputed election, under international pressure to find a way to share power. But the president angered the opposition by insisting his position as head of state was not negotiable.

President Mwai Kibaki and opposition leader Raila Odinga met for about an hour in the presence of former U.N. Secretary-General Kofi Annan, who succeeded where other mediators failed in getting the men to sit down together. Since the Dec. 27 vote, at least 685 people have been killed in riots and ethnic fighting and some 255,000 people have been forced from their homes.

After the meeting, Kibaki and Odinga walked out of the downtown presidential offices, shook hands and smiled.

"I will personally lead our country in promoting unity, tolerance, peace and harmony among Kenyans," Kibaki told reporters -- making a point of saying he had been "duly elected" as president.

At a news conference soon after Kibaki spoke, Odinga's Orange Democratic Movement condemned the president's comments.

"Calling himself the duly elected president negates the whole rationale for international mediation," said opposition spokesman Anyang Nyongo. He called for the "principles and agenda" of the mediation to be put down in writing "so that the process may formally commence."

He offered no details on Thursday's meeting besides saying only Odinga, Kibaki and Annan were in the room.

International allies, saying the vote tally was rigged, have been urging Kibaki and Odinga to negotiate a power-sharing agreement that might create a new position of prime minister for Odinga.

After Thursday's meeting, Odinga said he was focused on peace.

"Today we have taken the first vital steps in resolving the electoral dispute and conflict," he said. "I pledge to all Kenyans that my team and I will spare no effort to resolve this crisis."

The U.S. called the meeting a positive development.

"We think it is important that they do have face to face communication and dialogue and have an opportunity to resolve these differences," said State Department spokesman Tom Casey. "The Kenyans certainly deserve to have political leadership that is willing to work together to resolve these issues so that the country can move forward."

Previously, Kibaki had insisted on direct talks with Odinga, while Odinga had refused to meet without a mediator.

Uganda's President Yoweri Museveni, who met Kibaki and Odinga separately Wednesday, won an agreement from both sides to set up a judicial commission to investigate vote rigging, Ugandan presidential spokesman Tamale Mirundi said. But Odinga's spokesman Salim Lone said the suggestion "had not been ruled out" but had to be part of Annan's mediation efforts.

While politics sparked the postelection fighting, much of the violence also has been ethnic, pitting other groups against Kibaki's Kikuyu people, long dominant in politics and the economy in Kenya.

Aid workers reported scores of people were fleeing Molo, 100 miles northwest of Nairobi, in the western Rift Valley. Mobs in the Rift Valley earlier this week set dozens of homes ablaze and a man was burned to death in his car because he could not speak his attackers' language, according to police.

Human Rights Watch said it has evidence that opposition party leaders "actively fomented," organized and directed ethnic attacks in the Rift Valley.

The New York-based group, citing interviews with numerous members of the Kalenjin people native to the area, said its investigations indicated "opposition party officials and local elders planned and organized ethnic-based violence in the Rift Valley."

It said they "arranged frequent meetings following the election to organize, direct and facilitate the violence unleashed by gangs of local youth."

The rights organization said the same sources confirmed plans were being made to attack camps of displaced Kikuyu. It called for police to protect displaced people.

The allegations were vigorously denied by William Ruto, a senior opposition party official and legislator for one of 49 constituencies in the Rift Valley.

"For my constituency, nothing, absolutely nothing could be further from the truth. There was to the best of my knowledge, no organization that could put together the kind of logistics that could enable the kind of violence that we saw in that part of the world," Ruto told The Associated Press. "That was a spontaneous reaction to the (election) results."