A government statement read on state television yesterday said a state of emergency would be enforced in seven departments of the regions of Tillaberi and Tahoua.
Security forces would now be granted additional powers including the right to search homes at any time, it said.
The statement said repeated attacks in these areas "have endangered the security of the peaceful population and public order."
The zones affected are "Ouallam, Ayorou, Bankilare, Abala and Banibangou in Tillaberi and Tassara and Tilia in Tahoua".
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These include a late February attack in Ouallam which killed 16 soldiers and wounded 18. And in October, 22 soldiers died in Tahoua during a daring assault on a refugee camp.
Niger shares its southern border with Nigeria which has been struggling with a bloody seven-year uprising by the Boko Haram extremist group that has so far claimed more than 20,000 lives.
The insurgency began in northeast Nigeria but has since spread to Chad, Cameroon and Niger.
Diffa is home to more than 300,000 refugees and internally displaced people.