Interior Minister Alkache Alhada says the attack took place in the villages of Tchombangou and Zaroumdareye, near the border with Mali.

One hundred people were killed on Saturday in attacks on two villages in western Niger, Prime Minister Brigi Rafini said following one of deadliest days in recent memory for a country ravaged by Islamist violence.

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 for the attacks.

Security sources had said on Saturday that at least 70 civilians had been killed in simultaneous attacks by suspected fighters on the villages of Tchombangou and Zaroumdareye. At least 20 people were also wounded.

The attack is believed to be in retaliation to the earlier killing of two fighters by villagers, the minister added.

Al Jazeera’s Ahmed Idris, reporting from Niger’s capital Niamey, said the attack took place in one of the most porous areas of the border.

“Officials say they suspect the attackers crossed into Niger from neighbouring Mali. The area where the attack took place has also witnessed inter-communal violence. A government delegation is now on the way to the area to investigate what happened,” Idris said.

A local journalist told the AFP news agency that 50 people were killed in Tchombangou, while Reuters, citing a security source, said at least 49 were killed and 17 were wounded in the same village.

Another 30 were killed in Zaroumdareye, Reuters reported, citing a second security source.

The violence came on the same day Niger announced the results from the first round of a presidential election.

Former Interior Minister Mohamed Bazoum of the governing Nigerien Party for Democracy and Socialism was leading the vote with 39 percent of the votes. He will now face former President Mahamane Ousmane, who garnered 17 percent of the vote, in a runoff on February 20.

The area where Saturday’s attacks took place, Mangaize, is located in Tillaberi, a vast and unstable region where the borders of Niger, Mali and Burkina Faso converge.

Travel by motorbike has been banned in Tillaberi since January in a bid to pevent incursions by highly mobile rebel fighters riding on two wheels.

Fighters with links to al-Qaeda and the ISIL armed group have increasingly mounted attacks across West Africa’s Sahel region in recent years despite the presence of thousands of regional and foreign troops.

The violence has hit Mali and Burkina Faso the hardest, but has also spilled into western Niger. According to the United Nations, at least 4,000 people across the three nations died in violence linked to the armed groups in 2019.

On December 21, seven Nigerien soldiers were killed in an ambush in Tillaberi, while 34 villagers were massacred in the southeastern region of Diffa on the Nigerian border last month.

Manu Lekunze, teaching fellow at the University of Aberdeen in the United Kingdom, listed “growing population, poverty and climate change” as drivers of the instability in the Sahel region.

But Niger, Chad, Burkina Faso and Mali have “fundamental structural problems” where the states have become “incapable of providing security, whether individually and collaboratively” in the Sahel, Lekunze told Al Jazeera.

“We need to accept this fact and start thinking about how these states need to be fundamentally reformed to meet the challenges they are facing in the 21st century,” he said.