Boko Haram, the Nigerian Islamist group, has released a video showing some of the 276 schoolgirls kidnapped almost two and a half years ago.
Some 50 girls are shown with a gunman who demands the release of its fighters in return for the girls, and says some girls died in air strikes.
The Nigerian government says it is in touch with the militants behind the video.
The group is said to be holding more than 200 of the girls seized from a school in the northern town of Chibok in April 2014.
Many of the schoolgirls were Christian and were forcibly converted to Islam. It is feared that many have been sexually abused and forced into “marriage”.
The video begins with a shot of a masked man, carrying a gun, speaking to the camera. He says some girls have been wounded and have life-threatening injuries, and 40 have been “married”.
Speaking in the Hausa language, the gunman says the girls on display will never be returned if the government does not release Boko Haram fighters who have been “in detention for ages”.
He talks to a girl called Maida Yakubu. She asks parents to appeal to the government.
“To our parents – please be patient,” Yakubu said. “There is no kind of suffering we haven’t seen. Our sisters are injured, some of them have wounds on their heads and bodies. Tell the government to give [Boko Haram] their people, so we can come home to you.
“We are all children. We don’t know what to do. The suffering is too much. Please try. We have been patient. The only thing that can be done is to give them their people so we can go home.”
Maida’s mother, Esther, is one of several parents who recently published open letters to their daughters detailing the pain they feel at their loss and their hopes for the future.
Another girl standing in the background can be seen with a baby. Some girls can be seen weeping as Maida speaks.
The video ends with footage of bodies, said to be the victims of air strikes, lying on the ground in another place.
Boko Haram has waged a violent campaign for years in northern Nigeria in its quest for Islamic rule, and a faction of the group recently pledged loyalty to the so-called Islamic State.
Thousands of people have been killed or captured by the group, whose name can be translated as “Western education is forbidden”.
Nigerian Information Minister Alhaji Mohammed insisted the government was doing everything possible to secure the girls’ release.
“We are being extremely careful because the situation has been compounded by a split in the leadership of Boko Haram,” he said.
“We are also being guided by the need to ensure the safety of the girls.”
The video is the first to be seen since CNN obtained footage in April purportedly showing 15 of the girls.
The Chibok girls have been thought to be in a heavily forested area of northern Nigeria. Amina Ali Nkeki, a girl said to be one of those captured, was found wandering in the Sambisa forest in May by an army-backed vigilante group.