A senior Nigerian official has told the BBC that a would-be suicide bomber arrested in Cameroon is not one of the missing Chibok schoolgirls.
The girl had told investigators she was one of 270 abducted in Nigeria in 2014 by Islamist militant group Boko Haram.
She had explosives strapped to her body, had been drugged and was badly injured when she was arrested last week, Cameroonian officials say.
Boko Haram is increasingly using girls to carry out suicide bombings.
Nigerian President Muhammadu Buhari ordered a new investigation into the kidnappings in January, but admitted he had no information on the girls’ whereabouts.
The abductions of the schoolgirls from Chibok town in north-eastern Nigeria sparked international outrage and the #BringBackOurGirls social media campaign.
While about 50 of the girls managed to escape, 219 of the girls remain missing.
Boko Haram leader Abubakar Shekau has said some of the girls have been converted to Islam and forced to marry Boko Haram fighters.
There have been reports that some of them may have been forced to fight for the militant group, which is affiliated to Islamic State.
Although Boko Haram has been driven out from most of the areas it controlled in north-eastern Nigeria, it has continued to carry out suicide bombings and raids into neighbouring Cameroon, Chad and Niger.