Antananarivo  - An opposition campaign to unseat Madagascar's President Marc Ravalomanana ran into a series of roadblocks Tuesday, as opposition leaders were arrested or removed from power.

Diplomatic circles reported Tuesday that Andry Rajoelina, mayor of the capital Antananarivo, had been removed from office by Ravalomanana and replaced with Guy Rivo Randrianarisoa, a state secretary.

No opposition was reported from Rajoelina's camp Rajoelina had, on Tuesday, predicted the attempt to remove him from office.

Rajoelina has led the campaign to unseat the president, accusing Ravalomanana of authoritarianism and of lacking regard for the plight of the poor, among other things. He has led a campaign to have him stripped by the courts or by parliament of his powers.

However, the rebellion has always faced long odds. Madagascar's parliament remains firmly in the hands of Ravalomanana's supporters.

Also on Tuesday, six opposition leaders were arrested in the eastern port city of Toamasina, a local newspaper reported.

L'Express daily newspaper said the six were nabbed for planning a rally in support of Rajoelina. No official confirmation was immediately available.

On Tuesday, the 34-year-old mayor appealed to a crowd of supporters gathered in the city's May 13 square not to abandon the protest, but their subsiding numbers - around 15,000, compared to over 50,000 eight days previously - points to growing fatigue in opposition ranks.

Many Malagasy soured on the movement over the widespread rioting and looting that followed an opposition rally eight days ago. Over 100 people are reported to have died in the unrest.

Rajoelina plans to take his crusade to oust Ravalomanana on tour Wednesday, starting in the northern town of Antsiranana.

UN Secretary General Ban Ki-moon told an African Union (AU) summit in Ethiopia Monday he was "particularly concerned" about the developments in Madagascar and urged the parties to address their differences peacefully.

AU Commission chairman Jean Ping warned against any unconstitutional changes. dpa