Kenya's main opposition party has declared victory in the country's presidential election, despite continued delays in announcing official returns.

Musalia Mudavadi of the Orange Democratic Movement says Raila Odinga is Kenya's president-elect based on the party's own vote tally. Mudavadi is Mr. Odinga's vice-presidential running mate.

Partial official results released Saturday show Mr. Odinga with 3.7 million votes, compared to 3.4 million for incumbent President Mwai Kibaki.

The vote count was expected to be completed by Friday. Electoral officials say the delays are caused by high voter turnout and minor logistical problems.

Anger about the plodding official vote count has led to rioting in parts of Kenya. Demonstrators have stoned cars and set fires in the western city of Kisumu - a stronghold of Mr. Odinga. Fighting has also broken out between rival ethnic gangs in Kibera, a sprawling slum in the capital, Nairobi.

Mr. Odinga has repeatedly accused Mr. Kibaki of planning to rig the election - allegations the president has denied.

International observers say Thursday's voting was largely peaceful and free of election fraud.

About 14 million Kenyans were eligible to vote in the elections. To win, a presidential candidate must receive a majority of votes and at least 25 percent in five of Kenya's eight provinces. The rule was adopted in 1992 to ensure the president has broad support in a country often divided by tribal issues.

Some information for this report was provided by AFP, AP and Reuters.