The Nigerian army said it has captured the strategically significant town of Gwoza from Boko Haram.
Making the announcement on social media, the army said it had killed several members of the group and that a "mop-up" was now underway.
Nigerian media are reporting that more than two hundred of the girls captured in Chibok in April 2014 are being held in the town, in Bornea State.
A 56-year-old woman who was kidnapped by the group in 2014 and held in two locations by the group told the International Centre for Investigative Reporting that she was held along with the girls under very tight security in a house in Gwoza.
The town was first captured by Islamist fighter last year, and was declared the headquarter of the group's Caliphate.