GWOZA –– The Nigerian army says it has retaken the north-eastern town of Gwoza, believed to be the headquarters of militant Islamist group Boko Haram.
The insurgents had now been driven from virtually all the territory they had held, it said.
Some militants were now fleeing towards border areas, the military said.
News of Gwoza’s recapture comes a day before presidential elections, which were postponed by six weeks because of the offensive against Boko Haram.
Meanwhile, the president of Chad, which is helping Nigeria fight Boko Haram, has strongly criticized Nigeria’s military.
Thousands of people have been killed since 2009, when the group began its insurgency to create an Islamic state.
An estimated three million people have fled their homes because of the unrest, and many may be unable to vote.
BBC Africa security correspondent Tomi Oladipo says Gwoza’s capture is a major milestone for the Nigerian army.
The town is not far from Chibok, where Boko Haram kidnapped more than 200 schoolgirls from a boarding school last April.
Our reporter says Gwoza was one of the places where the militants were rumoured to be hiding the girls, who are yet to be found.
After his fighters captured Gwoza in August, 2014, the Boko Haram leader declared a caliphate in areas under his control.
The militants have been pushed back since Nigeria’s neighbours Cameroon, Chad and Niger sent troops
to help it earlier this year.
“These successful operations have culminated in the dislodgment of terrorists from towns and communities in Adamawa, Yobe and Borno states,” military spokesman Chris Olukolade said.
A lot of arms and ammunition were recovered and “a massive cordon and search has commenced to locate any of the fleeing terrorists or hostages in their custody”, he said.
Major General Olukolade also thanked Nigeria’s regional partners for their encouragement during the recent operations.
But Chad’s President Idriss Deby has been fiercely critical of Nigeria’s response, saying the Nigerian military had been uncooperative.
He told French magazine Le Point that Chadian troops have had to retake towns twice from Boko Haram because Nigeria’s forces had failed to secure them.
He estimated Boko Haram had 20,000 young fighters, some of whom had been trained by Islamic State in Libya, the AFP news agency reports.