The Nigerian Islamist group Boko Haram has released a video showing some of the schoolgirls they abducted from the northern town of Chibok.
Some 50 girls are shown with a gunman who demands the release of fighters in return for the girls, and says some girls died in air strikes.
The government says it is in touch with the militants behind the video.
A journalist who had contact with Boko Haram has been declared a wanted man by the Nigerian army.
The group is said to be holding more than 200 of the 276 final-year girls it seized from a school in April 2014.
Non-Muslims were forcibly converted to Islam, and it is feared that many of the schoolgirls have been sexually abused and forced into "marriage" by their captors.
Parents of the missing girls have described their anguish at seeing their daughters in captivity.
The video begins with a shot of a masked man, carrying a gun, speaking to the camera. He says that some of the girls have been wounded and have life-threatening injuries, and that 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".
I have seen her: Samuel Yaga, father of abducted schoolgirl Serah Samuel, talking to the BBC Hausa service
I have watched the video several times. I saw her sitting down.
The fact is we are overwhelmed with a feeling of depression. It's like being beaten and being stopped from crying. You helplessly watch your daughter but there is nothing you can do. It's a real heartache.
Those who are still alive - we want them back. We want them back irrespective of their condition.
As ordinary men, there is nothing we [the other fathers and I] can do on our own. We are just here unable to do anything with our lives. You see your child but someone denies you from having it. They are being forcefully married and they now live in terrible conditions.
The video concludes with footage of bodies, said to be the victims of air strikes, lying on the ground at another location.
The militant also carries out a staged interview with one of the captives, who calls herself Maida Yakubu, in which she asks parents to appeal to the government.
Maida's mother, Esther, is one of several parents of Chibok girls who recently published open letters to their daughters detailing the pain they feel at their children's absence and their hopes for the future.
Another girl among those standing in the background can be seen with a baby. Some of the girls can be seen weeping as Maida speaks.
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 so-called Islamic State.
Thousands of people have been killed or captured by the group, whose name translates as "Western education is forbidden". Many of the girls abducted in Chibok were Christian.
Bid to pressurise government? Analysis by Tomi Oladipo, BBC News, Lagos
Boko Haram has always maintained that the Chibok girls were safe and would only be released if the Nigerian government gave in to its demands.
Through this video, the group is again trying to make the government look like the villain for carrying out air strikes on the militants, which it claims have backfired and hit the abductees instead.
Reigniting public sympathy for the girls might be an attempt to force the government to listen. Boko Haram is attempting to paint the military campaign against the jihadists as a failure.
It is also significant that this video comes shortly after a split in the group, with one faction maintaining that it is the true regional branch of the so-called Islamic State. The video indicates that the other faction, led by Abubakar Shekau, is the one holding the Chibok girls and so it will use this to show why it cannot be ignored, even if its rivals have foreign backing.
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 the 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 Nigerian army declared journalist Ahmad Salkida a wanted man after he published details of the new video before it was released.
Salkida, who moved to Dubai a few years ago, has written extensively about the inside operations of the group.
The Chibok girls had been thought to be in a heavily forested area of northern Nigeria.
One of the girls was found wandering in the Sambisa Forest in May by an army-backed vigilante group.