Ten soldiers were slightly injured in the exchanges which broke out late Sunday after a large group of Islamist fighters arrived on motorbikes and cars, a member of the security forces said.
The Boko Haram fighters were “clearly well-trained and certainly well informed about our positions,” the source said.
The fighting took place in Gueskerou, a village in the West African country s southeastern region of Diffa bordering Nigeria, from where a bloody uprising by Boko Haram fighters has spilled over.
Government forces are working to identify the body of one of those killed who is believed to be a Boko Haram leader, according to the source.
The military pushed the fighters back towards Nigeria and seized firearms, munition and three vehicles, including one equipped with a mounted weapon stolen from the military in the town of Bosso last June, the source added.
Boko Haram s insurgency began in northeast Nigeria and has spread to Chad, Cameroon and Niger, claiming more than 20,000 lives and displaced 2.6 million people.
Niger declared a state of emergency in Diffa, home to more than 300,000 refugees and internally displaced people.