The military was pressing ahead with operations in the Sambisa Forest area of the northeastern state of Borno, where the Islamists have camps, said governor Kashim Shettima.
"They (soldiers) are already moving into the forest aggressively," Shettima told reporters at President Muhammadu Buhari's official residence in Abuja where he brought rescued student Amina Ali.
"They are expending a lot of resources and time in the Sambisa Forest. I am an eternal optimist. I believe that in the coming days and weeks more recoveries will be made."
Kaduna state governor Nasir El-Rufai said the discovery of Amina near the forest on Tuesday "raises our hope that others are still alive".
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"By God's grace, the operation going on in Sambisa, in a matter of weeks we will have all the girls back safe and alive," he added.
Amina Ali was been quoted as saying that all of the girls kidnapped more than two years ago were still being held in the former game reserve. But she said "six were already dead".
Defence Minister Mansur Dan Ali told Buhari at today's meeting with Amina Ali that the area of semi-desert scrub was "the haven of Boko Haram terrorists".
Seven soldiers have been killed in the operation -- four due to "enemy action" and homemade bombs and three in road accidents, he said. 69 Boko Haram fighters have been killed, he added.