One-time opposition leader Raila Odinga ahead in race for presidency against incumbent deputy president William Ruto, official results show.

Supporters of Raila Odinga, celebrate in the street ahead of contested presidential election results in Kisumu port city.
Supporters of Raila Odinga, celebrate in the street ahead of contested presidential election results in Kisumu port city. (AFP)

Veteran opposition leader Raila Odinga is leading Kenya's presidential race, official election results showed, pushing deputy president William Ruto into second place.

With just over 26 percent of votes counted, Odinga had 54 percent and Ruto had 45 percent, according to results provided by the Kenyan election commission and displayed on a large screen at a national tallying center in the capital, Nairobi, at midday on Saturday.

Ruto and Odinga are in a tight race to succeed President Uhuru Kenyatta, who has reached his two-term limit. Kenyatta fell out with Ruto after the last election and has endorsed Odinga.

East Africa's wealthiest nation and most vibrant democracy held presidential, parliamentary and local elections on Tuesday.

Official vote tallying has been proceeding slowly, fuelling public anxiety.

Election commission chairman Wafula Chebukati blamed party agents, who are allowed to scrutinise results forms before they are added to the final tally.

"Agents in this exercise cannot proceed ... as if we are doing a forensic audit," he told a news briefing on Friday.

"We are not moving as fast as we should. This exercise needs to be concluded as soon as possible."

Representatives from Odinga and Ruto's coalitions did not immediately respond to requests for comment.

READ MORE: Concerns mount as Kenya TV channels halt sharing election result tallies

Violence in previous polls 

Reuters news agency and other media outlets have been tallying results forms from 291 constituencies posted on the election commission website. 

These have not yet been verified, and this tally is running well ahead of the official one.

As of 2100 GMT, Reuters had tallied 241 forms, which showed Ruto in the lead with nearly 52.3 percent of the vote, compared to 47 percent for Odinga. Two other candidates had less than 1 percent between them.

Thirty other forms could not be included in the count because they were unreadable or were missing information such as signatures, constituency names, or totals.

The forms Reuters is tallying are preliminary and the results subject to change. 

After the forms are uploaded to the commission's website, Kenyan election law requires that they are physically brought to the national tallying centre, where party representatives can examine them for any discrepancies.

The process was designed as a safeguard against the kind of rigging allegations that have triggered violence after previous polls. 

More than 1,200 people were killed after a disputed 2007 election and more than 100 killed after a disputed 2017 election.

The winning candidate must receive 50 percent of the national vote plus one, and at least 25 percent of the vote from 24 of 47 counties.

The commission has until Tuesday to declare a winner.

READ MORE: Key faces, talking points: What to know about Kenya's presidential election

Source: Reuters