Kenyans voted on Thursday in presidential and parliamentary polls preceded by violence and soured by delays and charges from the main opposition challenger that the government was plotting to rig the result.

Police fired teargas to disperse an angry crowd in one district, as millions of people from the east African country's humid coast, its shantytowns and lush highlands took part in the closest contest since independence from Britain in 1963.

President Mwai Kibaki, 76, is vying for the top job with  former ally Raila Odinga, 62, who is determined to realise a long-held dream of leading the region's top economy.

Kibaki, whose National Rainbow Coalition unseated Kenya's 39-year ruling party in 2002, faces the possibility of losing his re-election bid despite a sound economic record and the backing of his Kikuyu tribe, the country's largest.

If Kibaki lost he would be Kenya's first sitting president to be ousted at the ballot box. Analysts say the chance of a second transfer of power in two elections shows democratic maturity. Others fear it heightens the potential for trouble.

Many of the 14 million eligible voters began queuing three hours before polling began at 6 a.m. (0300 GMT).

Chief EU election observer Alexander Graf Lambsdorff told Reuters that overall the voting was going well, and that he had seen no evidence of fraud so far.

"There are some technical problems but what is pleasing is that people are turning out to vote in large numbers and are doing so peacefully and patiently," he said.

Delays, however, stoked tensions in areas including Kuresoi, where local media said two people where hurt when police fired teargas to chase away voters furious their names were missing from registers.
    Tempers also frayed in Odinga's Nairobi constituency.

After complaining to the Electoral Commission of Kenya (ECK) that his name was also missing, Odinga was mobbed by fans as he returned to vote in Kibera, Kenya's biggest slum.
    He said the mix-up had been a "deliberate attempt" by the government to rig the outcome in his constituency.
    Kibaki's party said he had gone to the wrong voting booth and then straight to the media, "rather than seek guidance". It said his insinuation that certain tribes were being deliberately excluded from registers was "divisive and false".

The ECK agreed to extend voting by two hours there and at another polling station nearby.
    Kibaki, who voted near his home in Othaya, a fertile central region of tea and coffee farms, said he was sure of victory.

"Kibaki is a true leader," said Othaya businesswoman Wanjiku Muteru. "It's a shame loudmouthed people are spoiling his name."    

Many supporters of Odinga, a former political prisoner jailed by Kibaki's predecessor Daniel arap Moi, believe the Kikuyu have had it too good under the current administration.

"We didn't celebrate Christmas," said Feni Ojwang, a housewife in Odinga's Nyanza birthplace, a western region of picturesque valleys that belie its deep poverty.

"The goat and chicken I bought are still in the house. We will not slaughter them until Raila is declared winner."    

While Kenya enjoys a reputation as a haven of stability in a volatile region, it has a long history of election violence.

Odinga's Orange Democratic Movement (ODM) unleashed a last minute barrage of claims that Kibaki's Party of National Unity (PNU) was planning to steal victory on the eve of the vote.  The government denied it.

As tensions soared, mobs in Nyanza killed three policemen this week who they accused of being disguised as PNU agents to stuff ballot boxes.

Police boss Hussein Ali said 60,000 police and security agents were sent to more than 20,000 polling stations. He warned agitators: "If it m