Madagascar's electoral court has barred the incumbent president, Andry Rajoelina, and the wife of a long-standing rival from standing in the next presidential election, the court said.
The decision by Rajoelina and Lalao Ravalomanana, wife of the Indian Ocean island's previous leader, unseated by Rajoelina in a 2009 coup, to stand in the election led to donors suspending financing for the poll.
As a result, the vote has been delayed by a month to Aug. 23, and analysts say there are now doubts whether it will happen at all. The court also struck former president Didier Ratsiraka from the list of candidates.
It cited "an anomaly in the application of the law" but gave no further reasons for its decision. It was not immediately clear if the prospective candidates had recourse to appeal.
The African Union, the South African Development Community (SADC) and key donors such as France and the European Union had applied heavy pressure to try to prevent the candidacies.
Madagascar slid into turmoil that scared off investors and hurt the vital tourism industry after the former disc jockey Rajoelina seized power from Marc Ravalomanana with military support. Foreign donors froze budget support and the AU suspended Madagascar's membership.
Both men agreed in January not to contest the election. However, Rajoelina accused Lalao Ravalomanana of breaking this deal when she put herself forward in April after returning from self-imposed exile in South Africa, and rejoined the presidential race.
Neither Rajoelina nor Lalao Ravalomanana was immediately available for comment.
In a statement, the African Union said the removal of their names from the electoral list marked "an important step towards the creation of the conditions needed ... for a transparent and credible presidential election".
The pan-African body, which has said it would not accept the results of an election won by any of the three candidates, urged them to accept the court's decision.
Madagascar's economy shrank 4.6 percent in 2009, the year of the coup, after growing at 7.1 percent the year before. It is forecast to expand by just 2.6 percent this year, according to the World Bank.