The former UN secretary general, Kofi Annan, today urged Kenya's leaders to do "whatever possible" to stop the violence that threatens to engulf the country.
Speaking at Kenya's national assembly to mark the formal start of a mediation effort, Annan said there was an opportunity for Kenya's leaders to "take charge" and "steer this beautiful and prosperous country towards stability".
Annan struck an upbeat note while flanked by the president, Mwai Kibaki, and the opposition leader, Raila Odinga, in a choreographed effort at political reconciliation.
He said "short-term issues" - the violence that has claimed 800 lives since Kibaki's disputed re-election - could be settled in four weeks. Annan has urged the government to deploy the army to help the police force, which has been unable to control the situation.
Today, two military helicopters fired rubber bullets at a mob threatening members of the Luo tribe sheltering at a police post in western Kenya.
"The helicopters are dive-bombing the crowd and firing their guns," said a Reuters reporter in Naivasha, a town in west Kenya's Rift Valley, the scene of heavy violence at the weekend.
Naivasha, a town famous for its flower industry and tourism - the country's top two foreign exchange earners - has been simmering for the past week.
Police confirmed rubber bullets were fired from machine guns as the helicopters dived three or four times towards a crowd of more than 600 people brandishing machetes and clubs. Two police trucks were called in to evacuate the displaced Luos to safety.
The helicopters also opened fire elsewhere in the town. It was not immediately clear if there were casualties.
Yesterday in Naivasha, only a handful of police separated about 1,000 Kikuyu men armed with machetes and clubs from hundreds of Luo men who were forced from their homes at the weekend. The Kikuyus said they were avenging attacks elsewhere in the country by pro-opposition Luo and Kalenjin youths.
The president, Mwai Kibaki, appealed for calm, while the opposition leader, Raila Odinga, warned that the country was "drifting to anarchy".
In the Kibera slum of Nairobi, at least seven people were killed as thousands of people armed with machetes or makeshift weapons such as golf clubs and hockey sticks faced each other at the railway line that generally divides members of Kibaki's Kikuyu tribe from inhabitants of Odinga's Luo ethnic group.
Also in the capital, two gunmen killed an opposition MP. Mugabe Were was shot in the head as he drove to his house in suburban Nairobi, police said.
"We are treating it as a murder but we are not ruling out anything, including political motives," Kenyan police spokesman Eric Kiraithe said. "We are urging everyone to remain calm."
Were was one of the opposition MPs who won seats in the December legislative vote, held at the same time as the presidential election.
The US Democratic presidential candidate, Barack Obama, whose father was Kenyan, has appealed for peace on Nairobi's Capitol FM radio station.
"Now is the time for all parties to renounce violence. Now is the time for Kenyan leaders to rise above party affiliations and past ambitions for the sake of peace," Obama said.
The UN humanitarian aid chief, John Holmes, called on Kenya's political leaders to end the fighting. He said the violence had already led to the displacement of 300,000 people who now needed shelter and trauma counselling.
"They have to take responsibility for what is happening, for stopping it, for stopping people acting in their names," Holmes said. The UN's main fear, he said, was that the fighting would lead to a "sort of downward spiral of violence" that would become harder to stop.
Thousands of machete-wielding youths from Kikuyu and Luo tribes are roaming the Rift Valley, burning homes, blocking roads with burning tyres and clashing with outnumbered police.
Thousands of people have fled Rift Valley towns where more than 100 people have been killed since Friday.
Odinga's Orange Democratic Movement insists the December 27 presidential election was rigged in Kibaki's favour, a view shared by most western nations and all local and foreign observer groups.
Kenya has been plunged into its biggest crisis since independence by the subsequent violence, which has seen more than 800 people killed in clashes with police and ethnic attacks that have brought to the surface long-held tensions over land, the economy and political power.
Unrest yesterday spread as far as Lake Victoria, where thousands of youths poured into the downtown area of Kisumu, barricading roads and burning tyres. Several deaths were reported.
Joshua Nyamori, an opposition activist, said the latest demonstrations were sparked "by the killing of innocent Luos in Naivasha", which is 65 miles west of Nairobi. On Sunday, at least 11 people, mainly Luos, were killed there when their locked house was set on fire by a Kikuyu gang.
Deaths were also reported in Burnt Forest and Kericho, the heart of the tea industry, while a hotel and two large wholesale shops were razed in Kakamega.
"What is alarming about the last few days is that there are evidently hidden hands organising it [the violence] now," said Lord Mark Malloch-Brown, the British minister for Africa, Asia and the UN, during a visit to Kenya yesterday.
Despite the gravity of the situation - apart from the loss of life, Kenya's economy is suffering badly - Kibaki has shown no sign of a willingness to compromise. Instead, he has succeeded in alienating the countries that give him the most financial support: the United States and Britain.
After Kibaki's meeting yesterday with Malloch-Brown, who signalled his support for the mediation efforts led by the former UN secretary general Kofi Annan, the presidential press service released a statement entitled: "British government recognizes President Kibaki and his government."
A spokesperson for the British High Commission said the claim was patently false. Kibaki's assertion yesterday that a £1m donation from Britain would be used to resettle people displaced by the violence - who are mainly Kikuyus - was also described as "wrong and manipulated" by a diplomatic source.
On Sunday, Annan circulated a draft of his proposed agenda for negotiations between Kibaki and Odinga.
A spokesman for Odinga said yesterday the document was "something that we can work with as a start". The government's position is unknown, but Kibaki's spokesman said yesterday that he was likely to attend an African Union summit that starts in Addis Ababa, Ethiopia, on Thursday, meaning any negotiations may not begin until next week.
Until then, Kenyans are bracing themselves for further violence. In attacks that appear unrelated to the election chaos, but in keeping with the lawlessness in parts of the country, three foreigners have been killed in coastal towns in the past week. Graham Warren, 64, a Briton, was killed by robbers at his home in Watamu, north of Mombasa. In the southern resort of Diani Beach, two Germans were hacked to death by a gang that followed them into the house where they were staying.