* Winner Rajaonarimampianina backed by president Rajoelina
* Rajoelina ousted his predecessor in 2009 coup
* Rival says vote was rigged
* Political crisis has stunted economic growth
ANTANANARIVO, Jan 3 (Reuters) - Former Finance Minister Hery Rajaonarimampianina won Madagascar's run-off presidential election, the electoral commission (CENIT) said on Friday, but his main rival claims the vote was rigged.
CENIT leader Beatrice Atallah said Rajaonarimampianina, the candidate backed by President Andry Rajoelina who ousted his predecessor in a coup in 2009, won 53.5 percent of the Dec. 20 vote.
He beat Jean Louis Robinson, who ended up with 46.5 percent but has demanded a recount. Robinson's camp has filed almost 300 complaints to the electoral court, which now has to rule on the result.
The poll, the fist since former disc jockey Rajoelina grabbed power, is meant to end a crisis that has driven out investors, cut aid flows and sharply slowed the economy.
A disputed result could prolong the malaise on the politically volatile Indian Ocean island and delay restoring the external budget support needed to drive public spending and boost anaemic growth.