Men, women and children bearing machetes and clubs chanted opposition slogans in the slums of the Kenyan capital Nairobi Thursday as a second day of protests over disputed presidential election polls got violently underway.

Protestors in Mathare shantytown, unable to break a police barrier to reach the downtown rally called by the opposition, burned tyres and furniture as police stood on guard nearby with their fingers on triggers.

The opposition Orange Democratic Movement (ODM), which has called three days of rallies, said at least 17 people have been killed nationwide since protests restarted Wednesday.

"Under the orders of the government, the police are executing innocent citizens at will while the world watches and talks about dialogue. How do you dialogue with killers?" defeated presidential candidate Raila Odinga told reporters.

ODM has vowed to defy a ban on rallies and urged its supporters to demonstrate for three days against the disputed presidential election results that brought President Mwai Kibaki back to power for a second term.

Witnesses said police fired live rounds into the disgruntled crowds, killing at least two people in Mathare, in a continuing cycle of violence that has gripped the usually peaceful East African country.

"Police came and shot, and took the bodies. What had they come to do? Kill and go? They are supposed to protect us," said Awatt Awatt, an opposition supporter.

Scenes were similar in areas around the country, as police fired shots into the air to disperse crowds.

Odinga compared Kibaki to Zimbabwe's leader Robert Mugabe, charging he was dragging Kenya into a "cesspool." He said more than 1,000 people have been killed in the post-election period, most by gunshot.

Security was intensified Thursday, as police fended off protestors with water cannons and tear gas and blocked off central Nairobi's Uhuru Park, where the opposition has tried to demonstrate in vain..

"We are not going to change the situation unless we resist. Liberation has never come on a silver platter," said Rono Kipchirchir, tightly clutching a large wooden club.

The ODM charged Kibaki with stealing the win in last month's election and has pledged not to cease mass action until he admits that claim and the votes are recounted.

International election observers also called the election flawed and Odinga has urged Western powers to impose sanctions on Kibaki.

Police sealed protestors in their slums in the capital as the first of three days of rallies kicked off Wednesday. Officers lobbed tear gas at even the smallest crowds in the coastal town of Mombasa, Nairobi and Kisumu, an ODM stronghold.

The alleged irregularities in the vote have sparked unrest across the country with at least 600 people killed according to the Red Cross and about 250,000 displaced in events that mark a disturbing change in Kenya.

While beset by corruption and poverty, Kenya has seen steady economic growth to become the regional powerhouse and is viewed as an anchor of stability in a volatile region.