NAIROBI - Kenyan police fired teargas to disperse stone-throwing supporters of the country's main presidential contenders on Monday after the candidates made a final push to win votes in a race deemed too close to call.

Scuffles briefly flared shortly after President Mwai Kibaki and his opposition challenger, Raila Odinga, addressed huge rallies in the capital on the last day of campaigning before Thursday's election.

Hawkers and shoppers fled as rival supporters, crossing paths in downtown Nairobi, hurled stones at each other before the police arrived and fired teargas canisters at the crowds.

"These elections are spoiling my Christmas. It's very tough this year," said Lucy Mungua, who was caught up in the melee.

"No one wants to lose or be beaten."

With the latest opinion polls showing a couple of percentage points between the one-time allies, Kenyans fear the closeness of the contest will provoke rigging and more violence in the relatively young east African democracy of 36 million people.

Seeking a second term, Kibaki promised to pursue his record of economic growth and free schooling as thousands of supporters, wearing the blue of his Party of National Unity (PNU), sang and danced in the blazing sun.

"Everybody can see the work I have done in the past five years," he told crowds gathered at Nairobi's main Uhuru (Freedom) Park. "You all know what we have been doing and I am asking for your votes so that I can continue working."

Looking relaxed in an African print shirt, the 76-year-old incumbent took a dig at Odinga, who along with some of his aides was sacked from Kibaki's cabinet in 2005 for opposing a government-backed charter.

"They were in government but were defeated by the work."

At a sports stadium a few miles away, Odinga hit back saying if elected his government would do away with the old guard.

It was a pointed reference to Kibaki, a legislator since independence in 1963, and his predecessor Daniel arap Moi, who ruled for 24 years and has thrown his weight behind Kibaki.

"We will not be an exclusive club of grumpy old men," said Odinga, himself a longtime politician, warning Kibaki he would not accept a "fraudulent election".

DEMOCRATIC TEST

Trading on Kibaki's failure to stamp out corruption, Odinga vowed to fight graft that he said had cost the country more than 200 billion shillings ($3.15 billion) and tackle the widening gap between rich and poor.

"For every shilling a poor Kenyan earns, the rich one takes 66 shillings. That is the truth going by the government's own figures. But they prefer to trumpet 6 percent growth, without telling Kenyans where the money goes."

Some 14 million Kenyans are eligible to vote in Thursday's presidential and parliamentary polls. Official results are expected to start trickling in on Friday morning.

Many in Kenya are encouraged by the fact that the main challenger has a chance at victory -- a rare feat in African politics where ruling parties control state machinery and sitting presidents almost never lose re-election bids.

But, police have warned politicians against fuelling clashes which threaten to tarnish the election, a test of Kenya's democratic advances since the largely peaceful handover of power from a "Big Man" ruler to the opposition five years ago.

That in itself won wide praise. But Kenya remains plagued by tribalism and weak political parties dominated by personalities rather than ideology.

Kibaki has the support of his Kikuyu ethnic community, the largest of Kenya's 40 or so tribes, and is also popular in the northern and eastern provinces.

Odinga, a former political prisoner, enjoys the backing of his western Luo community, but has also garnered support from other ethnic groups who think the Kikuyus have had it too good under Kibaki.