Cameroonian troops have carried out an operation in the northeastern part of the country, eliminating at least four members of the Boko Haram terrorist group, Xinhua news agency reported, citing security sources.

A senior military official in the region said the military offensive began Sunday evening in the Walassa region in the far north.

Boko Haram has stepped up attacks on civilians in the region since January. Last week, militants kidnapped about 20 people in separate incidents, local police said. Some of the hostages were later found dead.

Boko Haram has been active in Cameroon's far north region since 2014.