The Nigerian army says it has retaken the north-eastern town ofBaga, held by Boko Haram militants since 3 January.
In a tweet from its official account, the army added that there had been heavy casualties and that "mopping up" operations were continuing.
Boko Haram killed scores of people when they attacked Baga, although the exact number is unknown.
Nigeria, Chad, Cameroon and Niger recently formed a military coalition against the Islamist militants.
It is not yet clear whether other armies were involved in the recapture of Baga.
However, the Chadian army spokesperson told the BBC's Thomas Fessy that there had been no involvement from his country's troops.
In recent months, Boko Haram has seized control of much of Nigeria's north-east, amid widespread criticism of the Nigerian army.
But backed by its neighbours, the army has recaptured some territory in recent weeks.
Last week, Nigeria retook the north-eastern towns of Monguno and Marte from the group.