(Adds Museveni, Annan mediation plans)
By Tim Cocks and Nick Tattersall
NAIROBI, Jan 20 (Reuters) - Attackers hacked three people to death with machetes in a slum in Kenya’s capital on Sunday in ethnic clashes triggered by President Mwai Kibaki’s disputed re-election last month, witnesses said.
Armed police chased away youths in Nairobi’s Huruma neighbourhood, whose name means "mercy" in Swahili, and some residents started to leave with their belongings on their heads.
"I saw three people dead, killed by pangas (machetes), slashed on the head, cuts on the back and a hand chopped off," said Samuel Oduor, 22, a freelance cameraman.
Other witnesses confirmed the death toll from fighting between youths from Kibaki’s Kikuyu ethnic group and the Luo tribe of opposition challenger Raila Odinga.
They bring the number of dead to at least 34 since the opposition launched three days of anti-government demonstrations on Wednesday. Many were killed by police opening fire on protesters, others by ethnic gangs.
"No need to kill somebody because of his tribe, even if he did not vote for me," Odinga told several hundred supporters as he came out of a church service in Nairobi’s Kibera slum, its roads blackened with the remains of days of flaming barricades.
Odinga said a memorial service would be held at a sports field in central Nairobi on Wednesday for those who had died and repeated a call for more demonstrations from Thursday, despite police orders to prevent rallies.
"You can beat our body, but you cannot break our spirit of justice," he told cheering supporters, some holding up banners reading "Raila our solution" or "Kibaki hand over to Raila".
More than 650 people have been killed since Kibaki was sworn into office after a disputed Dec. 27 election the opposition says was rigged and observers said was seriously flawed.
Police in the Rift Valley said they had found two more bodies near the village of Kipkelion, 180 km (112 miles) northwest of Nairobi, bringing the death toll there to 8 after armed men attacked a camp housing refugees on Saturday.
The violence has tarnished Kenya’s image as a stable nation in a troubled region, undermined its democratic credentials and laid bare the underlying tribal sentiments behind its politics.
A flyer apparently from the Mungiki, an ethnic Kikuyu gang notorious for brutal attacks and lucrative protection rackets, was circulated outside the church where Odinga spoke.
It warned Luos living in Kibera of reprisals.
"It is now known ... that the Luo had predetermined to cause chaos," said the printed flyer, whose authenticity could not immediately be verified.
"It is time that their aggression is halted forthwith without delay, therefore Mungiki taking control," it said.
After a heavy presence in recent days, police were conspicuous by their absence in Kibera as Odinga left the church but were in Huruma where the latest killings took place.
Residents said there had been sporadic fighting through the night between Kikuyus and Luos in Huruma. Police were not available for comment.
"They are beating us. They want to chase us away. They are armed with bows and arrows and they are killing our children," Wangeci Mwangi, 75, said of the gangs.
EU Aid Commissioner Louis Michel, who met Kibaki and Odinga on Saturday, has urged both to hold talks and end the killing.
Odinga said he would meet former U.N. Secretary-General Kofi Annan on Tuesday. Annan had been due in Kenya last week but delayed his trip due to flu.
The Ugandan Foreign Ministry said President Yoweri Museveni would also travel to Kenya in the next few days to mediate. Museveni is one of few African leaders to have congratulated Kibaki. Opposition supporters have questioned his impartiality.
"Museveni leave Kenyans alone," read one banner in Kibera. (Additional reporting by Bosire Nyairo and Joseph Sudah, Francis Kwera in Kampala; Writing by Nick Tattersall and Tim Cocks; Editing by Jon Boyle)