Madagascar's election campaign opened Tuesday ahead of presidential polls next month, as divisions over replacement candidates plagued the camps of major disqualified politicians.

Campaigning will last a month and finish a day before the October 24 poll meant to end a four-year political crisis on the Indian Ocean island sparked when strongman Andry Rajoelina ousted then-president Marc Ravalomanana in a coup.

But supporters are divided over new candidates after Rajoelina and Ravalomanana's wife Lalao, along with a few others, were barred from running under international pressure.

After the presidential polls, a parliamentary vote will follow on December 20, along with a second presidential round if the October election does not deliver an outright winner.

The new dates were reached following two earlier postponements amid a lack of funding and controversy over the candidacies of three top contenders.

An electoral court last month disqualified Rajoelina, Lalao Ravalomanana, and a former president after the three refused to withdraw from the presidential race.

Their candidacies, which did not meet electoral rules, had been widely condemned.