Kenyan opposition leader Raila Odinga has rejected early results of a presidential election that showed he was losing to incumbent and long-time rival Uhuru Kenyatta, stoking fears his supporters could take to the streets.
Early on Wednesday, the election commission website put Kenyatta ahead by 55.1 per cent of votes counted to 44 per cent for Odinga - a margin of nearly 1.4 million ballots with more than 80 per cent of polling stations reported.
Kenyatta, a 55-year-old businessman seeking a second five-year term, had held such a lead since the start of counting after Tuesday's peaceful vote, the culmination of a hard-fought contest between the heads of Kenya's two political dynasties.
But Odinga, a 72-year-old former political prisoner and self-described leftist, rejected the results as "fictitious" and "fake", lashing out in a late-night news conference at which he said his party's own tally put him ahead.
"We have our projections from our agents which show we are ahead by far," Odinga said, questioning why published results were not accompanied by scanned copies of forms signed by all party agents in polling stations.
Alleging vote-rigging, he also brought up the unsolved torture and murder of a top election official just over a week before the vote.
"We fear this was exactly the reason Chris Msando was assassinated," he said.
Odinga's comments carry ominous echoes of 2007 when he cried foul in an election marred by major irregularities.
About 1200 people were killed in a campaign of ethnic violence that followed.
Odinga also ran and lost in 2013 but quelled potential clashes by taking his complaints about the widespread failure of electronic voting equipment to court.
There were no signs of trouble in Kisumu as dawn started to break.
The son of Kenya's first vice-president, Odinga is an ethnic Luo in the west, an area that has long felt neglected and resentful of their perceived exclusion from power.
Kenyatta, the son of the first president Jomo Kenyatta, is a Kikuyu, the ethnic group that has supplied three of the four presidents since independence from Britain in 1963.