Niger, Chad and Cameroon are seeking to pin down Boko Haram within Nigeria’s borders ahead of a ground-and-air offensive by a regional taskforce due to start from the end of next month, a senior Niger military official said.

The Islamist group, which has killed thousands of people in a six-year insurgency in Nigeria, has fought fierce battles with the three countries’ armies in southern Niger and northern Cameroon, near Nigeria’s borders, in recent weeks.

Chadian forces have made incursions into Nigeria to push back the jihadist fighters, hundreds of whom have been killed. Military chiefs will meet in the Chadian capital N’Djamena next week to finalise strategy for the 8,700-strong taskforce of troops from Chad, Cameroon, Nigeria, Benin and Niger, said Colonel Mahamane Laminou Sani, director of documentation and military intelligence of Niger’s armed forces.

“All we are doing right now is stopping Boko Haram from entering Niger: if they attack our positions we push them back a certain distance and Nigeria pushes from the other side to contain the situation,” he said, on the sidelines of the annual US-sponsored ‘Flintlock’ counter-terrorism exercises in Chad.

“There are initiatives by our countries to make sure Boko Haram doesn’t get out of control but we have a deadline of end-March to put the joint force into practice,” he said late on Wednesday.