Prime Minister Brigi Rafini said 100 people were killed by Jihadists on Saturday in attacks on two villages in western Niger Republic.
Rafini announced the death toll in remarks broadcast on national television on Sunday from a visit to the zone, near the border with Mali.
He did not say who was responsible.
Security sources said on Saturday that at least 70 civilians had been killed by suspected Islamist militants on the villages of Tchombangou and Zaroumdareye.
Niger has suffered repeated attacks by militants linked to al Qaeda and Islamic State near its borders with Mali and Burkina Faso.
Saturdays attacks came on the same day that the electoral commission announced the results from the first round of the election to replace President Mahamadou Issoufou, who is stepping down after a decade in power.
Ruling party candidate Mohamed Bazoum, who finished in first, expressed his condolences on Sunday to the victims.