Eight people were killed and 36 wounded in clashes between riot police and opposition supporters in the Ethiopian capital Tuesday, a sign of persistent political tension in the Horn of Africa nation.

Police said six protesters and two policemen were killed in violence between armed riot police and stone-throwing protesters. The demonstration was seen by many as a new backlash against a disputed May election in the nation of 73 million people.

"Police have taken steps to bring to justice leaders of the opposition who they consider to be responsible for the deaths," a police statement said.

The disturbances were the first in Addis Ababa since post-election clashes killed 36 people in June, in the capital's worst violence in four years.

Tuesday's violence broke out three days after Ethiopia's main opposition party, the Coalition for Unity and Democracy, called for fresh protests over results of an election it says was rigged.

Party officials said police arrested seven of their leaders, including Berhanu Nega and Mesfin Wolde-Mariam, a human rights campaigner.

Ambulances rushed casualties to two hospitals as police armored personnel carriers patrolled the central Mercato area. Demonstrators set up roadblocks of burning tires and smashed car windshields.

Many of the wounded said the police attacked first, but authorities said those who were shot had tried to attack police.

Political tensions in Ethiopia have intensified since the country's second real multi-party vote handed Prime Minister Meles Zenawi a third five-year term.

The goodwill generated by the openness of the campaign dissipated following opposition claims of intimidation by the ruling party.