Kenya's opposition leader on Monday cancelled planned nationwide protest rallies amid fears they could ignite new bloodletting after violence that has already killed nearly 500 people.

Raila Odinga said he wanted to give mediation a chance, making the announcement at a news conference after meeting with US envoy Jendayi Frazer.

The government of President Mwai Kibaki, accused by Odinga of stealing a presidential election last month, had said the proposed Tuesday demonstrations were illegal and could provoke violence.

''We are therefore informing our supporters countrywide that tomorrow there will be no public rallies as we had called for countrywide. We will be issuing a statement once the dialogue starts,'' Odinga said.

''We want the discussions and the negotiations to take place in a peaceful environment,'' he added.

Odinga noted Ghana's President John Kufuor, the current chairman of the African Union, was expected to arrive by Tuesday on a mediation mission.

Kufuor's trip had been repeatedly delayed as the government rejected outside mediation.

Odinga and President Mwai Kibaki have both expressed openness to some form of power sharing to resolve the crisis.

Kibaki was declared winner of December 27 elections after a vote tally that Odinga and international observers charged was flawed.

In some areas, protests over Kibaki's victory have degenerated into ethnic rioting pitting other tribes against Kibaki's Kikuyu, long dominant in politics and the economy in Kenya.

A statement on Monday from the Ministry of Special Programmes put the toll at 486 dead with some 255,000 people displaced from their homes.

The toll was compiled by a special committee of humanitarian services set up by the government that toured areas most affected by riots and protests.