The toll from Friday's attack could rise as 16 people are still missing and 13 soldiers were wounded, a ministry statement said, according to Lemonde.
The troops were on patrol in the north of Banibangou department when they "came under a complex ambush by a group of armed terrorists", it said.
The statement also said several attackers were killed during the fighting but did not specify how many.
The attack took place in Niger's vast western region of Tillaberi, which straddles Burkina Faso and Mali and has faced repeated attacks since 2017 by armed groups linked to Al-Qaeda and ISIL terrorists.
The region neighbors the Tahoua area, where heavily armed attackers stormed a camp housing refugees from neighboring Mali last week.
Nine people were killed in that assault, which a local official said was carried out by "heavily armed terrorists" on motorcycles who fled back into Mali. All the countries involved are former French colonies.
MNA/PR