"We have evidence the results we have received have been doctored," he said.

He said the vote count should be stopped but added that his comments were not a call for protest.

Mr Odinga has been trailing behind his rival, Uhuru Kenyatta. There have been severe delays in counting as the electronic system has crashed.

The head of the electoral commission has warned it may be Friday or even Monday before there is an official result, the BBC's Gabriel Gatehouse reports from the Kenyan capital, Nairobi.

The credibility of the count is crucial to avoiding further bloodshed, our correspondent says.

More than 1,000 people were killed in the violence which broke out in 2007-08 after Mr Odinga claimed he had been cheated of victory by supporters of President Mwai Kibaki, who is stepping down after two terms in office.
Mr Kenyatta, who backed Mr Kibaki, is due to stand trial at the International Criminal Court (ICC) next month, accused of organising attacks on members of ethnic groups seen as supporters of Mr Odinga. He denies the charges.
Fall in rejected ballots

"We as a coalition take the position the national vote-tallying process lacks integrity and has to be stopped and re-started using primary documents from the polling stations," Mr Musyoka said on Thursday.

"It is not a call to mass action. We are committed as a coalition to the principle of the rule of law."

Following glitches with hi-tech voting and counting systems earlier this week, the vote-tallying process was started again from scratch, and by hand, on Wednesday.

Results were only being announced after the ballots had been physically delivered to election headquarters in the capital, rather than being filed electronically.

The latest figures indicate Mr Kenyatta has maintained his lead over Mr Odinga, with 2.5m (53%) votes to 1.9m (42%) - as originally indicated.

However, the new figures show that the number of rejected ballots, which has been a major issue, has sharply come down.

In the initial count, some 300,000 votes - about 6% - were disqualified for various reasons.

This figure has now come down to about 40,000. While the reason for the drop remains unclear, some observers said that election officials were being too strict first time round.

Mr Kenyatta's camp had rejected calls for some of these ballots to be included, as requested by Mr Odinga's allies.

The winning candidate must get more than 50% of the total votes cast and at least 25% of votes in half of the 47 counties - the latter was a requirement introduced in the new constitution to make sure the new president wins with wide support rather than only with the backing of voters in his regional and ethnic strongholds.

If there is no clear winner, a second round of voting will take place, probably on 11 April.