A documentary on the Warsaw Ghetto has been given an adult “R” rating by the Motion Picture Association of America (MPAA), triggering concern whether historical footage on starvation and death can be shown in high schools for educational purposes.

The film’s distributor, Oscilloscope Laboratories, announced immediately that it will appeal the decision. Beastie Boy Adam Yauch, founder and head of Oscilloscope, said: “MPAA has really gone too far this time. It’s b******t.”

Yael Hersonski, the Israeli director of the documentary, put it more politely. She said: “I realise this may be a difficult film to watch, but it enables us to approach the Holocaust in particularly illuminating way.

“I wish I had had a chance to see such films as a teenager, and I think high school teachers should have the opportunity to decide whether to use it in their classes,” added Ms Hersonski, whose grandmother was a Warsaw Ghetto survivor.

Mr Yauch and Ms Hersonski will appeal the MPAA rating at a hearing on August 5, with the board expected to come up with a final verdict the same day.

In its original “R” rating, which bars viewing the film to anyone under 17 unaccompanied by a parent or guardian, MPAA cited the documentary’s “disturbing images of Holocaust atrocities, including graphic nudity”. The latter was a Nazi-coerced scene of five young women in a mikveh.

“An Unfinished Film” consists mainly of four reels of raw footage shot in the Warsaw Ghetto in 1942.

Long considered authentic, a recently discovered fifth reel shows that the project was part of a planned, but never released, Nazi propaganda movie.