Updated

Police fired tear gas and bullets to disperse thousands of protesters in several Kenyan cities at the start of three days of opposition rallies, killing at least one person and injuring half a dozen.

Opposition leader Raila Odinga, who insists he was robbed of the presidency through vote rigging in last month's election, urged his supporters to join the protests nationwide despite a government ban.

• Click here to view photos.

• Click here for more riot pictures.

In downtown Nairobi, helmeted riot police on horseback chased away small clusters of protesters from skyscraper-lined streets. Businesses quickly shut as tear gas was fired, and thousands of panicked office workers in suits and high-heels streamed out of downtown on foot.

"I don't want to get caught up in that tension," said research student Julius Rotich who was among the crowds fleeing.

Some people angered by the protests shouted "Raila go home!"

Police in several cities lobbed tear gas canisters and beat protesters with batons to disperse them. In Nairobi and at least two other cities, police fired live rounds, sending crowds scrambling for cover.

Odinga vowed he would lead the march himself on Nairobi's Uhuru Park downtown, which is ringed by riot police. Speaking earlier to reporters at his party headquarters, Odinga said: "Nothing will stop us from mounting these rallies."

Violence in the wake of Kenya's disputed Dec. 27 vote has left more than 600 people dead and a quarter of a million displaced. The unrest has marred Kenya's image as a stable democratic oasis in a war-ravaged region and damaged its tourist-dependent economy. It has also aggravated long-simmering ethnic tensions and tribal conflicts over land ownership.

The violence had eased since a previous round of opposition protests earlier this month.

National police spokesman Eric Kiraithe had no word on casualties Wednesday, but nurses in Kisumu said at least one man was killed and three wounded there. In Nairobi, at least three men were taken to a hospital after they were shot and wounded in the Kibera slum, one of two areas in the city where police fired tear gas and bullets to disperse hundreds of protesters.

The opposition was bolstered Tuesday by the election of their candidate for parliament speaker, but Odinga's supporters promised to continue protesting until President Mwai Kibaki and his government acknowledge that his re-election was compromised.

Kiraithe said turnout for the rallies was low nationwide and people were getting tired.

"They want to go on with their daily businesses," Kiraithe said. "You can't demonstrate every day. People want to send their children to school. They want to put bread on their table. Political issues can be solved politically."

Protests Wednesday touched the coastal city of Mombasa, where police hurled tear gas and used batons to beat back several hundred protesters.

In the western towns of Kisumu and Eldoret, thousands of rowdy young men massed in the streets, first marching peacefully. As the crowds grew, police lobbed tear gas canisters, forcing them disperse. They regrouped, and police then fired live rounds, immediately clearing out downtown streets in both towns.

"The police are overreacting. People are just demanding their rights," said one of the wounded in Kisumu, 26-year-old Dominic Okoth, where burning tires blocked roads and sent columns of smoke into the air. "Police officers should serve their people, not shoot them."

When police opened fire in Eldoret, a crowd of about 4,000 fled. Workers at a nearby gas station crouched under cars for safety, their heads in their hands.

Earlier in Kisumu, protesters carried a coffin with Kibaki's name on it. In Eldoret, some had erected makeshift roadblocks on the outskirts of town. On one, a dead dog was draped over a pile of rocks with a sign that said "Kibaki Death."

"We are going to keep up the pressure from every legal angle and through all peaceful means until the government agrees to acknowledge that the election results were false and that a solution must found to the political crisis," Odinga spokesman Salim Lone told The Associated Press.

Foreign and local election observers have said the vote count in the Dec. 27 presidential election was deeply flawed. And although the electoral chief pronounced Kibaki the victor, he later said he had been pressured to release the results and did not know who won.

On Tuesday, lawmakers chose Kenneth Marende, a 52-year-old lawyer and opposition supporter, to be the new speaker of the National Assembly in a narrow 105-101 vote over a Kibaki loyalist.

In an interview published Wednesday in the Kenyan Daily Nation newspaper, U.S. Ambassador Michael Ranneberger said it was not possible to say who won last month's vote because it was "not transparent."

According to official results, Kibaki beat Odinga by 230,000 votes out of around 10 million ballots cast.

"But our analysis that the vote was extremely close highlights the need for political accommodation between two sides," Ranneberger said.