Hamas released a video late on Monday of Mia Schem, one of the nearly 200 people believed to be held hostage in Gaza after the group launched a cross-border assault on Israel nine days ago.

The 60-second video — the first released by the group — begins with Schem, 21, receiving medical treatment for a wound above her right elbow and shows her arm being wrapped in bandages by a person off camera.

The next image is of Schem, who disappeared from the site of a music festival where at least 260 people were killed, speaking directly to the camera in Hebrew.

“At the moment I am in Gaza,” Schem says in a solemn, clipped voice. She says that she is being looked after and that her arm was operated on for three hours at a hospital. The video ends with her plea to be returned to Israel.

“I just ask that I be returned as fast as possible to my family, to my parents, and to my siblings,” she says. “Please get us out of here as quickly as possible.”

Israel said Hamas was “trying to portray itself as a humane organisation, while it is a murderous organisation responsible for the murder and abduction of babies, women, children and elderly”.