The United Nations says it is sending a special envoy to Madagascar to examine ways the world body can help avert further violence in the country, after riots led to the deaths of an estimated 100 people.

The United Nations says Haile Menkerios, the U.N. assistant secretary-general for political affairs, will visit Madagascar for four days beginning on February 7.

The world body says the government of Madagascar invited Menkerios, and he will meet with government officials and other concerned parties.

In a statement Thursday, U.N. Secretary-General Ban Ki-moon says he remains concerned by the tense political situation in Madagascar.

Madagascar's main opposition leader, Andry Rajoelina, has been leading a series of rallies and protests against President Marc Ravalomanana. An estimated 100 people died when the protests turned violent last week.

On Tuesday, government officials fired Rajoelina from his post as mayor of the capital, Antananarivo. However, Rajoelina has rejected the move and has appealed to both the Constitutional Court and parliament to remove the president from office.

Rajoelina has said he will form a transitional government on Saturday if the president, who he accuses of being a dictator, refuses to resign.

Crowds attending the mayor's rallies this week have been consistently smaller than those at last week's events.

President Ravalomanana has said that he remains in charge of the country.