At least five people have been killed in a bomb blast in Niger’s southern border town of Diffa amid growing Boko Haram militancy in the region.

A bomber detonated explosives near a market on Sunday after the army repelled an assault by the Nigeria-based Boko Haram militants on the border region, local witnesses said.

"There was fighting between security forces and elements of Boko Haram who tried to enter the town," a military source said, adding, "Fighting is taking place around the bridge at Doutchi. There are many dead."

Boko Haram terrorist group, which is considered the biggest security threat in Nigeria, has also conducted attacks in the neighboring countries of Cameroon, Chad and Niger.

The fight against Boko Haram has taken on a regional dimension. Benin, Cameroon, Niger, Nigeria and Chad have pledged to send 87,000 troops, police and civilians to defeat the Takfiri militants.