Tensions bubbled to the surface in the Kenyan parliament Tuesday as the house reopened for the first time since disputed presidential polls set off a political stalemate and ignited violence around the country that has killed nearly 600.

The opening session continued into evening as members voted in a speaker and were set to be sworn in as the rival political parties took their fight to parliament.

Legislators exchanged sharp words as voting was under way, and was then restarted because of a kerfuffle over a secret ballot rule that was allegedly broken by the opposition.

"We went into the elections with a secret ballot and then you stole the vote," said William Ruto, a member of the opposition Orange Democratic Movement (ODM).

Observers feared ODM, whose leader Raila Odinga claims the presidential polls were rigged, would provoke an argument by sitting in chairs belonging to government members, but the house opened orderly as lawmakers were set to elect a speaker.

Kenya's newspapers have urged ODM to use its great numbers in the house - it has 99 seats compared to 43 in President Mwai Kibaki's Party of National Unity (PNU) - to push legislation and policies its way.

After the first round, the ODM-backed candidate Kenneth Marende won with 104 votes to the candidate supported by the ruling PNU, Francis Ole Kaparo's, who won 99.

Two more rounds were expected.

Odinga has said ODM's attendance Tuesday was not an endorsement of Kibaki's win and the group would continue to seek a political solution to its grievances.

A small demonstration walked through downtown Nairobi carrying mock coffins and black crosses bearing the words RIP democracy, but the gathering was broken up by police.

While the European Union and other observers said the presidential vote was flawed, the parliamentary polls, held on the same day, were deemed largely credible and showed Kibaki's government a vote of no confidence with more than half his cabinet ousted.

Riot police carrying shields and batons were deployed across the capital Nairobi Tuesday ahead of the re-opening, part of the heavy police presence that has continued throughout the weeks following the December 27 elections.

Most roads leading into the downtown area and around parliament were sealed and tensions remain high as three days of opposition rallies in some 25 cities are set to begin Wednesday, in what may stoke tensions further and increase violence nationwide.

The opening of the house comes as former United Nations secretary general Kofi Annan is set to arrive to kick off a new round of mediation between the two sides, but the last attempt by the head of the African Union, John Kufuor, failed to bring a resolution.

The Kenyan Red Cross has said 575 people have been killed since clashes erupted after last month's elections, but some reports put the number closer to 700.

Some calm has returned to the country, but camps for the internally displaced have sprouted up to house the nearly 300,000 Kenyans who have been forced from their homes.

The violence has marked a disturbing change in the East African country known as a beacon of stability in a turbulent region, and has ignited ethnic tensions that have been bubbling below the surface for decades.