Six Nigerien soldiers were killed and three others wounded in the country's southeast Wednesday in an attack blamed on Boko Haram, the interior ministry said in a statement read on state radio.
The soldiers were killed in an ambush "by Boko Haram terrorists" at around 6 am as they were patrolling some 20 kilometres (12 miles) from Diffa, the regional capital near Nigerian border, the statement said.
Boko Haram has suffered substantial setbacks in recent months in the face of a counteroffensive by national armies from the region.
At least 17,000 people have been killed since Boko Haram launched an insurgency in 2009 to carve out an Islamic state in northeast Nigeria.
More than 2.6 million people have fled their homes since the start of the violence but some of the internally displaced have returned home after troops began the fight-back last year and recaptured territory.
A regional force involving troops from Nigeria, Chad, Cameroon, Niger and Benin is to deploy to fight the Islamists.