Niger guards have held President Mohamed Bazoum inside the presidential palace in Niamey, the country’s capital.
Reuters also said the presidential guards have been blocked off the palace by military vehicles since Wednesday morning.
The development has been likened to the four military coups that have plagued neighboring Mali and Burkina Faso since 2020.
Ministries next to the palace have also been blocked off, and staff inside the palace have not been able to access their offices, presidency and security sources said.
The rest of Niamey appeared calm, with normal morning traffic on the road and full internet access, Reuters said.
Previous coups in Burkina Faso and Mali were spurred in part by frustrations over authorities’ failure to stem an Islamist insurgency blighting the Sahel region, which includes Niger.
There was also a thwarted coup attempt in Niger in March 2021, when a military unit tried to seize the presidential palace days before Bazoum was due to be sworn in.