Scores of ethnic Fulani herders were killed in a raid involving a state-backed militia operating alongside Nigerian soldiers, local sources told AFP.
The operation targeted herding settlements near Kabe in Borgu, Niger state, following accusations the victims acted as informants for Ansaru militants.
Witnesses said vigilantes from Nigeria’s Bussa district and neighbouring Benin joined the assault, which also led to sweeping arrests of young men.
Security personnel reportedly moved door-to-door, detaining suspects and shooting those who resisted during the coordinated raids on Thursday.
A local leader, Ahmad Ali, said 41 suspected informants were killed, describing the operation as a joint effort involving vigilantes and soldiers.
A humanitarian source placed the death toll slightly lower at 38, attributing the violence to cross-border vigilante groups from Nigeria and Benin.
Nigeria’s military declined immediate comment, while Beninese authorities have not confirmed awareness or involvement in the operation.
The killings unfold against a backdrop of prolonged insecurity in Niger state, where banditry, kidnappings, and jihadist infiltration have deepened local fears.
Ansaru, an al-Qaeda-linked group, has expanded its presence in the region, sometimes overlapping with criminal networks that raid villages and disrupt livelihoods.
Analysts warn that Fulani communities are increasingly stigmatised as militant sympathisers, fuelling cycles of reprisals that risk further radicalisation.
Residents said tensions escalated after two suspected informants were killed, prompting threats from herders to disrupt farming activities during the rainy season.
In response, vigilantes launched what locals described as a pre-emptive raid, fearing attacks on farmers working in remote fields.
Following the violence, herding settlements were abandoned, with survivors fleeing the area alongside their cattle, leaving a landscape marked by fear and uncertainty.