Hundreds of Islamist Boko Haram militants attacked a military post in Diffa, South Niger, killing 16 soldiers.
The attackers also injured no fewer than nine other soldiers, the Ministry of Defence said in a statement on Wednesday.
The statement added that the army in a counterattack also killed 50 of the militants in the resulting combat.
The insurgents regularly cross over from neighbouring Nigeria.
Last week, Nigerian President Mohamed Bazoum called on the international community to take action against the insurgents it is fighting on two fronts – the rebel group Jama’at Nasr al-Islam wal Muslimin (JNIM), which is affiliated with al-Qa’ida, in the west, and Boko Haram in the east.
“Against the Islamic State (IS) in Iraq, we saw a large international coalition. But today we see no mobilization through the UN,” he said in a recent interview with The Economist.
He said the country and its neighbours have enough soldiers to fight Islamic rebel groups but need financial and air support.