A video that appears to be from Boko Haram says some of the abducted Chibok schoolgirls have been killed in Nigerian air strikes and shows one of the alleged victims pleading for authorities to release detained militants so the girls can be freed.

The video posted Sunday on Twitter shows a veiled girl identified as one of the 276 students abducted from a remote school in northeastern Nigeria in April 2014, saying some classmates died in aerial bombardments and 40 have been "married" to Islamic extremist fighters.

The video, posted by a Nigerian journalist, shows a fighter warning that if the government battles Boko Haram with firepower, the girls will be killed.

It says the Chibok girls are held by Boko Haram leader Abubakar Shekau. Some 218 schoolgirls remain missing.