Mr Amadou was prime minister of Niger for seven years
Niger's parliament has lifted the immunity of former Prime Minister Hama Amadou, opening the way for him to be prosecuted for alleged corruption.
The BBC's Idy Baraou in the capital, Niamey, says MPs approved the motion by 72 to 28 in a tense session.
Mr Amadou is accused by President Mamadou Tandja's government of embezzling state funds.
But he claims he is the victim of a politically motivated campaign to stop him standing for president in 2009.
A former close ally of Mr Tanja, Mr Amadou resigned as prime minister last year after a vote of no confidence, but remains the leader of Niger's governing party.
The West African nation is one of the poorest countries in the world.
Our correspondent says the MPs debated late into Monday night after a 24-hour session in parliament.
Mr Amadou is expected to appear in Niger's High Court in the coming days, where he will face charges of embezzling 100m CFA francs (more than $237,000), our reporter says.
If found guilty, Mr Amadou could face a jail term, which would mean the end of his political career, he says.
He was in power for seven years, and left office in 2007 under the cloud of another corruption scandal.
That case, in which some $9m of European Union aid was allegedly taken between 2002 and 2006, led to the detention of two former education ministers.
Mr Amadou denied any wrongdoing, but opposition MPs were angered by his refusal to attend a parliamentary investigation into the scandal.