Hundreds of Boko Haram militants attacked a military post in southeastern Niger overnight, killing 16 soldiers and wounding nine more, the defence ministry said on Wednesday.
About 50 of the Islamist militants were killed in the resulting combat in the West African country's Diffa region and significant quantities of weapons were recovered, the ministry said in a statement.
The attack late targeted the town of Baroua, where thousands of residents had only just returned after taking refuge elsewhere following jihadist massacres in 2015.
The Boko Haram insurgency broke out in northeastern Nigeria in 2009, but violence frequently spills over into neighbouring Chad, Niger and Cameroon in the Lake Chad Basin.
In December, an attack blamed on Boko Haram killed 28 people and burned 800 homes in the Diffa region.
More than 6,000 people had returned to Baroua in late June under a programme to encourage around 26,000 inhabitants in the region to leave safer villages or UN camps and go back to their homes.
The authorities said they had beefed up security to provide returnees with greater protection.
The world's poorest country by the benchmark of the UN's Human Development Index (HDI), Niger is facing jihadist attacks on two borders, with Islamist militants also carrying out cross-border raids from neighbouring Mali.
(FRANCE 24 with REUTERS, AFP)