Nigeria's military has said it has rescued 200 girls and 93 women from a Boko Haram stronghold, but said there was no confirmation the hostages were those kidnapped from Chibok a year ago.
An army spokesman gave no indication as to how long it would take for the hostages to be identified.
Boko Haram said it abducted 276 girls from a secondary school in Chibok, also in Borno, on 14 April 2014.
Fifty-seven girls escaped within hours of the attack but 219 remained in captivity.
In the weeks following the mass abduction, Nigerian security sources and locals in Borno said there were indications the girls had been taken to the Sambisa Forest.
But defence officials and experts agreed that they were likely separated over the past 13 months, casting significant doubt on the possibility that they were being held together as a group.
Boko Haram's leader, Abubakar Shekau, vowed to "marry them off" or sell them as "slaves".
The Chibok attack brought unprecedented world attention to the Nigerian Islamist uprising.
Celebrities and prominent personalities including US First Lady Michelle Obama joined the Twitter campaign #BringBackOurGirls that attracted supporters worldwide.
Boko Haram has also been blamed for hundreds of other kidnappings, especially targeting women and girls across northeast Nigeria.
