Armed groups have killed more than 100 Nigerian soldiers and captured an "enormous" stock of weapons in clashes in northeast Nigeria since December 26, according to a report published on Friday by a UN-led group of aid agencies in Chad.

The report by the aid groups, dated January 17, said attacks by armed groups had intensified over the past few weeks, which could force people to flee to Chad if the attacks are not stopped by the Nigerian army.

This is a developing story and will be updated.