At least 71 Nigerian soldiers were killed on Tuesday in an attack on a military camp in the west of the country, according to the defence ministry.
The attack took place at the camp that is located near Niger’s border with Mali, All Africa news website reported.
On Wednesday, the assault was carried for long three-hours by “heavily armed terrorists estimated to number many hundreds,” the ministry said in a statement.
57 of the attackers had also been killed, the statement further added.
No militant group has claimed responsibility for the attack so far, but fighters linked to the Islamic State (IS) terror group and Nigeria-based Boko Haram are active in the area, the BBC said.
The attack comes just after the Niger government requested a three-month extension to a state of emergency, first declared two years ago.
President Mahamadou Issoufou cut short a trip to Egypt to return home following the “tragedy” that took place at the base in Inmates, near the border with Mali, the presidency said on Twitter.
There was no immediate claim of responsibility for the attack, which is believed to be the deadliest against Niger’s military in living memory.
Tuesday’s attack came a few days before French President Emmanuel Macron scheduled a meeting next week, in the southwestern French town of Pau, with five presidents from the Sahel to discuss security in the region.
Niger is part of a five-nation task force known as the G5, set up in 2014 with Burkina Faso, Mali, Mauritania and Chad.
Thousands of civilians and soldiers have died in violence across the vast Sahel region, which began when armed fighters revolted in northern Mali in 2012.