By Lovasoa Rabary
ANTANANARIVO (Reuters) - Madagascar's former president has filed a legal challenge to his successor's choice of prime minister, creating new political uncertainty in the Indian Ocean island as it struggles to rebuild its economy.
President Hery Rajaonarimampianina named air force commander and businessman Jean Ravelonarivo as prime minister this week, handing him the task of dealing with mounting complaints about blackouts and other problems that led his predecessor to quit.
But the appointment was contested on Friday by Andry Rajoelina, a former coup leader who seized the presidency in 2009 but left office after a 2013 election and now leads the biggest party in parliament.
Any prolonged political dispute could deter investors. The economy, based on reserves of nickel, cobalt, gold, uranium and other minerals, went into freefall after the coup, which drove away international donors.
The peaceful vote in 2013 has helped restore aid but the economy is still on its knees and the government cannot afford fuel for power stations.
Rajoelina said the way the new premier was appointed was not constitutional. His position was outlined in a document presented to court by his MAPAR party, which holds 49 of parliament's 151 seats, and its allies.
It was not clear when any ruling might be issued.
Rajoelina has said he does not plan protests, but one analyst said tensions could rise if MAPAR and its allies sought to secure more portfolios in cabinet, delaying the formation of a government and much-needed reforms.
Robert Besseling, analyst at IHS Global risk consultancy, said the president appeared to be trying to centralize power in ignoring one of the nation's main political groups.
The International Monetary Fund, which resumed relations with Madagascar after the 2013 vote, has said reforms should include scrapping fuel and power subsidies. It says the state cannot afford them and they do not help the poor.
(Writing by Edmund Blair; Editing by Mark Trevelyan)