Skirmishes between police and youths have broken up a memorial service for opposition victims of the post-poll violence in Kenya's capital, Nairobi.
The memorial was for those who died in last week's violence
Tear gas was fired into the crowds of mourners after supporters of the Orange Democratic Movement stoned police cars.
Meanwhile, former UN chief Kofi Annan began a fresh attempt to end the chaos arising from the disputed election.
ODM leader Raila Odinga later said he had called off mass protests in Nairobi planned for Thursday at his request.
"We believe as ODM that given a good chance, we can get out of the quagmire that our country is embroiled in," ODM MP William Ruto told KTN television afterwards.
Before the meeting, Mr Annan said he would insist on a solution for the "sake of Kenya and its people and for the sake of Africa".
His main goal is to establish a dialogue between President Mwai Kibaki and opposition leader Raila Odinga who says his election victory was stolen.
Mr Annan is accompanied in his mission by Graca Machel, the wife of former South African President Nelson Mandela, and former Tanzanian President Benjamin Mkapa.
"I am confident that, in this crucial endeavour, we can count on the will, maturity, resourcefulness and judgment of the leaders," Mr Annan said late on Tuesday.
President Yoweri Museveni of Kenya's neighbour Uganda is also in the country and held talks with President Mwai Kibaki.
The BBC's Amber Henshaw in Nairobi says the air was thick with tear gas as riot police fired canisters into crowds of people who had gathered for a memorial service in one of Nairobi's parks.
ODM youths were outraged by a police presence
The wooden coffins of those killed in last week's crackdown on poll protests had been taken from the mortuary and laid out on the ground for people to pay their respects.
She says hundreds of mourners had gathered round to listen to prayers and speeches and Mr Odinga was rounding up his speech when tear gas canisters started to fly.
Reports say a group of ODM youths were angered by the presence of police at the venue and started pelting their cars with stones and the meeting then descended into chaos.
The protest moved down the street; demonstrators then set fire to the telephone exchange building where the government-owned telecommunications company Telkom was based.
Earlier, a group of commuters in the east of the city were attacked by about 30 unidentified armed men. Police say three people were killed and there have been eight arrests.
Hospital officials in Kenya say the political violence that followed the poll has brought a big rise in rape.
One UN agency spoke of an opportunistic atmosphere for gangs of men.
On Tuesday, the opposition filed a complaint with the International Criminal Court, accusing the government of crimes against humanity.
It says the police used excessive force during last week's protests, in which more than 30 people died.
In the latest violence, four people were hacked to death as at least seven were killed in the Rift Valley.
More than 650 people have been killed in protests, while 250,000 more have fled their homes since the 27 December elections.