This aerial view shows trenches surrounding Monguno to protect it against incursions by Boko Haram groups, in Monguno, Borno state.

Several hundred people kidnapped by Boko Haram earlier this year from a village in the northeastern state of Borno were freed over the weekend, a senator and local youth leader said Sunday.

Kidnappings, often for ransom, have become a key tactic of Boko Haram jihadists in their 17-year-old insurgency against the Nigerian state, mostly concentrated in the northeast.

Samaila Kaigama, president of the Borno South Youth Alliance (BOSYA), said his group "has secured the release of all the 416 women and children abducted from Ngoshe".

They were released Saturday, Kaigama told journalists.