The United Nations said Friday it was seeking contact with Niger coup leaders after they stopped its agencies and other organisations from working in military "operation zones".

"We've seen the reports. We are reaching out to the de facto authorities in Niger to better understand what this means and the implications for the humanitarian work," UN spokeswoman Alessandra Vellucci told reporters in Geneva.

Her comments came after Niger's interior ministry late Thursday announced it was stopping UN agencies, NGOs and international organisations from working in military "operation zones".

It did not specify which regions were affected, but said the measures were "due to the current security situation".

"All activities and or movements in the zones of operations are temporarily suspended," it said.

Niger's new military leaders took power in a coup on July 26, when troops ousted President Mohamed Bazoum.

Among the justifications they gave for unseating the democratically-elected leader was the dire security situation in the landlocked former French colony in the heart of the Sahel.

Niger is battling two jihadist insurgencies -- a spillover in southeastern Niger from a long-running conflict in neighbouring Nigeria, and an offensive in the southwest by militants crossing from Mali and Burkina Faso.

But since the coup, the attacks have continued, including one near the Burkina Faso border on August 15 that killed 17 troops.