Much of the Chadian force fighting Boko Haram in Nigeria has withdrawn to Cameroon and is deploying farther south, Chadian soldiers and a Cameroonian military official said on Thursday, signaling the potential start of a new offensive.

Chad¡¯s military has spearheaded an operation by Nigeria¡¯s neighbors against the Islamist militant group that has killed thousands in northeast Nigeria and in recent months mounted an increasing number of cross-border raids.

Nigeria has simultaneously launched an offensive to retake a series of towns with the backing of hundreds of mercenaries from South Africa and the former Soviet Union in a bid to secure towns ahead of a rescheduled March 28 election.