Gunmen have killed an opposition member of Kenya's parliament, sparking a new wave of violence in the country. As Nick Wadhams reports from Nairobi, there are fears the violence has devolved into revenge attacks between the country's ethnic groups.

Women cry outside house of opposition lawmaker Mugabe Were where he was gunned down in Nairobi, 29 Jan 2008

Women mourned outside the home of Mugabe Were, who was gunned down just hours before. Were was a member of opposition leader Raila Odinga's Orange Democratic Movement and was elected to Kenya's parliament in the December 27 national election.

The killing sparked new clashes in the nearby Kibera slum, a stronghold of Mr. Odinga. One doctor was reportedly beheaded by men with machetes, and rioters again uprooted a railway that runs through the slum.

Police spokesman Eric Kiraithe said investigators are not ruling out the possibility that the killing was politically motivated, but he refused to comment further.

Opposition leader Raila Odinga (3rd R) mourns over the body of ODM MP Mugabe Were who was shot dead, 29 Jan 2008

Mr. Odinga, who has maintained that President Mwai Kibaki's re-election in the December 27 vote was rigged, said there is no doubt the killing was political.

"It is despicable that a member of parliament should be assassinated in this manner," he said. "We have witnessed five bullets that were shot into his body, two of them into his eyes. These were people who had planned an assassination. This is not an ordinary murder as the police spokesman would want the country to believe. This is a planned political assassination."

Government spokesman Alfred Mutua refused to comment on the attack.

His killing was a new escalation in violence that has claimed at least 850 lives since the vote and more than 100 in recent days. Much of the recent killing has been concentrated in Naivasha and Nakuru, two cities just north of Nairobi.

On Tuesday, helicopters opened fire with what officials said were rubber bullets on crowds fighting each other in Naivasha.

Member of Kikuyu tribe living in Kibera slum is carried to safety after attack by members of opposing tribe during ethnic clashes in Nairobi, 29 Jan 2008

The recent violence appears to be partly motivated by revenge. Kikuyus, who primarily support President Kibaki, apparently are avenging attacks on members of their ethnic group who have been killed or fled violence further northwest.

Luos, Luhyas and Kalenjin, who generally support Mr. Odinga, say they are striking back against what they believe are injustices committed by the Kikuyu.

There was some hope that Mr. Kibaki and Mr. Odinga could edge closer to compromise in negotiations mediated by former U.N. Secretary-General Kofi Annan.

While both sides say they are ready for negotiation, their starting positions are far apart. Mr. Kibaki says his election as president was legitimate and he will not negotiate on that point. Mr. Odinga has demanded the president's resignation and new elections.