Air Marshal Alex Barde made the comments
"We want our girls back. I can tell you that our military can and will do it, but where they are held, can we go there with force?''
"Nobody should say Nigerian military does not know what it is doing; we can't kill our girls in the name of trying to get them back.''
He added: "The good news for the parents of the girls is that we know where they are, but we cannot tell you. ... We cannot come and tell you the military secret. Just leave us alone; we are working to get the girls back."
Meanwhile Nigeria's ex-president Olusegun Obasanjo has met with people close to Boko Haram in an attempt to broker the release of more than kidnapped schoolgirls.
According to the source, Obasanjo supported a prisoner-for-hostage swap that would see some of the girls released in exchange for a group of Boko Haram fighters held in Nigerian custody.
As a private citizen whose ties to the presidency have been damaged, Obasanjo likely does not have the authority to negotiate any deal on the government's behalf.