Nigerien soldiers have announced the removal of President Mohamed Bazoum from office.
They said they had dissolved the constitution, suspended all institutions and closed the nation’s borders.
Amadou Abdramane, a colonel-major, made the announcement in a televised address late Wednesday evening.
“We, the defence and security forces… have decided to put an end to the regime of President Bazoum,” Abdramane said while being flanked by fellow soldiers.
He added that they had dissolved the constitution, suspended all institutions and closed the country’s borders.
Niger President Mohamed Bazoum has been held by troops from the presidential guard since early on Wednesday.
He was promised Washington’s “unwavering support” in a call from US Secretary of State Antony Blinken.
UN Secretary General António Guterres also said he had spoken to the president and offered the UN’s full support to the uranium-rich country.
Bazoum is a key Western ally in the fight against Islamist militancy in West Africa.
Two neighbouring countries, Mali and Burkina Faso, have experienced coups triggered by jihadist uprisings in recent years.
In both countries the new military leaders have fallen out with France, the former colonial power, which also formerly ruled Niger – a vast, arid country on the edge of the Sahara desert and one of the poorest nations in the world.
Bazoum’s whereabouts are unclear but in a statement on Twitter on Thursday morning he said the “hard-won gains will be safeguarded” and that Nigeriens who love democracy will see to it.
Foreign Minister Hassoumi Massoudou has declared himself the head of state and called on all democrats to “make this adventure fail”.