Madagascar's opposition leader said he is breaking off talks aimed at ending weeks of political unrest after President Marc Ravalomanana failed to show up for the latest round of negotiations Wednesday.

Opposition leader Andry Rajoelina told reporters that the president's absence from what would have been the fourth round of talks showed his lack of concern for the Malagasy people.

Earlier in the day, the chief mediator in the crisis said he was quitting.  Roman Catholic Archbishop Odon Razanakolona said the talks were completely deadlocked and making no progress.  

He called on the United Nations to help find a solution to the standoff.

About 100 people have died in political unrest in the weeks since Rajoelina began a campaign of demonstrations and civil disobedience aimed at ousting Mr. Ravalomanana.

The opposition leader earlier declared himself the country's new ruler and vowed to take over the government.  He was the mayor of the capital, Antananarivo, until the president fired him after the protests turned violent.

Rajoelina accuses Mr. Ravalomanana of being corrupt and authoritarian. The president has repeatedly said he remains in charge of the nation's affairs.