"Consequent upon the directives of the president ... The Defence Headquarters will be releasing from detention a number of persons being held in connection with terrorist activities," a defence statement said, adding it included "all women under custody."
Islamist extremist group Boko Haram has previously demanded the release of women prisoners, though the defence statement made no mention of the demand.
"The move is in furtherance of the federal government position in response to requests by the presidential committee on dialogue and reconciliation," the statement said.
It came as Nigeria pressed ahead with a nearly week-old offensive targeting Islamist insurgents in the country's violence-wracked northeast.