In the footage, a man says he has been held for 40 days, suggesting the video may have been recorded in mid-November.

A lot of blood is seen on a tiled floor, as well as military equipment, which Hamas claims to have captured.

The video ends with gruesome images of a bloodied body that appears to be that of the same hostage seen earlier.

We are withholding the man's name - he says this and his age in the video.

A script in Arabic says that Israeli soldiers "failed to reach" the hostage, leading to his death, and that the Israeli team "quickly fled the place".

It claims that the Israel Defense Forces (IDF) used an ambulance to reach the place where the hostage was being held.

The BBC has not verified the video and has no confirmation of the claims made by Hamas in it.

At a briefing on Friday evening, chief IDF spokesman Daniel Hagari confirmed that two Israeli soldiers were seriously wounded during operations in Gaza to free hostages.

He said "terrorists who participated in the kidnapping and holding of hostages" had been killed, but he said no hostages had been released.

It is not clear if he was talking about the same incident described in the Hamas video or something else.

The IDF launched its military operation in Gaza after a deadly Hamas attack on Israel on 7 October.

Israel says 1,200 people were killed and 240 taken hostage in the Hamas attack. A number of hostages were later released during a short-lived ceasefire - but not those who Hamas claims to be linked to the Israeli military.

Hamas says Israel has killed more than 17,177 people in its retaliatory campaign, including about 7,000 children.

By Paul Adams