At least 30 people have been killed in a weekend of continuing post-election violence in Kenya, reports say.
Nairobi's slums have seen some of the worst violence
In the worst incident 22 people in a Rift Valley camp for displaced people reportedly died after being attacked by mobs armed with machetes and arrows.
Three were also killed with machetes in a Nairobi slum and a further five died in unrest elsewhere in the country.
Former UN Secretary General Kofi Annan is due to meet political leaders on Tuesday as part of mediation efforts.
EU Development Commissioner Louis Michel has already been trying to mediate an end to the crisis over the presidential vote.
He met President Mwai Kibaki and opposition leader Raila Odinga and urged both sides to stop exacerbating tensions.
Meanwhile, Kenya's Foreign Ministry has called in Britain's High Commissioner in Nairobi Adam Wood to complain about the government's criticism of President Kibaki's re-election.
Kenya's Foreign Minister Moses Wetangula said he was angered by remarks last week in which Foreign Office Minister Meg Munn said London did not recognise his government - although few governments have recognised the outcome of the controversial poll.
The bodies of the three killed in Mathare slum on Sunday bore machete marks.
Witnesses said the violence had an ethnic angle, pitting members of Mr Kibaki's Kikuyu community against Luos like Mr Odinga.
Houses have been burned down and people forced from their homes
An Associated Press reporter saw the body of one man who was beaten to death, apparently a Luo caught by a group of Kikuyus.
Another man staggered past, blood streaming from his mutilated arm after a machete attack, the reporter adds.
A Luo woman who spoke to Reuters news agency said she had been asked what tribe she was from.
"Even before I could tell them, they took my bag and even wanted to cut me with a machete," she said.
"I was just saved by the grace of God, they have taken everything I had."
Musalia Mudavadi, an official from Mr Odinga's Orange Democratic Movement (ODM), visited the injured in hospital and attacked the actions of the police.
"Now we are seeing cases of the police actually giving way and allowing people to attack each other," he told AP.
In the Rift Valley, 22 people sheltering in an improvised displacement camp at Kipkelion have been attacked and killed with machetes and arrows in the past three days.
There were also reports of five people being killed at Elburgon, also in the Rift Valley, as a mob of more than 150 people armed with improvised weapons attacked villagers burned their homes.
The BBC's Adam Mynott says much of Kenya remains peaceful, but areas that have experienced ethnic tensions are still very dangerous.
Despite protests from aid agencies, camps for displaced people in Nairobi and Mombasa are being shut down.
The government argues that the affected parts of the two cities are now safe and affected people may now return to their homes.
Supporters of Mr Odinga, who accuses President Kibaki of stealing the 27 December election, say they will resume protest rallies on Thursday.
In Kisumu in western Kenya, where some 100 people have died in the violence, ODM leaders are attending a large inter-denominational prayer session at the main stadium to remember the victims.
The disturbances across the country have left more than 600 people dead and a quarter of a million homeless.
Mr Michel, who met political leaders from both sides in Nairobi, said he was concerned that the Kenyan police were using excessive force against opposition demonstrators.
But he also criticised the opposition's decision to resume mass rallies which could lead to more violence.
"Now there is a need for a military ceasefire and also for a semantic rhetoric ceasefire," he said.
"Now we need a quiet situation, we need just a little bit positive silence."
The ODM, which wants a re-run of the election, had originally called off protests in favour of a boycott of companies that back President Kibaki.
Kenya's National Commission on Human Rights cast doubt on the vote, listing a catalogue of irregularities on Friday.