At least 25 soldiers have been killed in a suspected jihadist attack on a military camp along the western border with Mali, Niger's army says.
More than 60 militants were also killed when the army - supported by partners - responded with air power, it says.
Last month, 71 soldiers were killed in an ambush claimed by an affiliate of the Islamic State group in the region.
Along with its neighbours, Niger has been hit by an upsurge of violence by Islamist militants in West Africa.
The Thursday attack in Chinagodrar base, about 209 km (130 miles) north of the capital Niamey, comes just days before France, which has thousands of troops in the region, hosts West African leaders to assess military operations in the Sahel region.
BBC
Russia's unmanned Luna-25 spacecraft has crashed into the Moon after spinning out of control, officials say.
Donald Trump has confirmed that he will not take part in Republican presidential debates with his rivals in the race for the White House.