Emmanuel Macron has said France will withdraw its ambassador and end all military cooperation with Niger following a coup.
He added that military cooperation was “over” and French troops would leave in “the months to come”.
A military junta seized Niger on July 26, deposing President Mohamed Bazoum.
The decision follows months of animosity and protests against the French presence in the country, with regular demonstrations in the capital Niamy.
The move deals a hammer blow to France’s counter-terrorism operations in the Sahel and France’s influence in the region, but Mr Macron said France would “not be held hostage by the putschists”, speaking to France’s TF1 and France 2 television stations.
There are around 1,500 French soldiers in Niger.
The French president said that he still regarded Mr Bazoum, currently held prisoner by the coup leaders, as the country’s “sole legitimate authority” and had informed him of his decision. He described the deposed president as a “hostage”.
Niger’s military leaders told French ambassador Sylvain Itte he had to leave the country after they overthrew Mr Bazoum on July 26.
However, a 48-hour ultimatum for him to leave, issued in August, passed with him still in place as the French government refused to comply, or to recognise the military regime as legitimate.
Mr Macron’s statement also comes hours after Niger’s coup leaders banned “French aircraft” from flying over the country.
The regional air safety organisation, ASECNA, said that Niger’s airspace was “open to all national and international commercial flights except for French aircraft or aircraft chartered by France including those of the airline Air France”.
The air space would remain closed for “all military, operational and other special flights”, unless receiving prior authorisation, the message said.
Air France told the AFP news agency simply that it was “not flying over Niger airspace”.