The Nigerian army has retaken the north-eastern town of Baga, held by Boko Haram militants since 3 January.
The army said that "mopping up" operations were continuing.
It also claimed in a separate statement that it had killed many Boko Haram militants, though this has not been independently verified.
Nigeria says 150 people died when Boko Haram took Baga and nearby Doron Baga, but locals said up to 2,000 died, according to the (BBC).
In a statement, Maj. Gen. Chris Olukolade said that "a large number of terrorists ... drowned" in Lake Chad and others were killed in the fighting to take the fishing town.
Boko Haram, which controls of much of Nigeria's north-east, has killed thousands of people.
In recent months it has also carried out cross-border raids in neighbouring Chad, Cameroon and Niger, attacking villages and military bases.
All three countries have joined Nigeria to form a military coalition against the Islamist militants.