A provocative documentary screened in Cannes depicts Prince Philip as a psychopath and the British royal family as racist “gangsters in tiaras.”

“Unlawful Killing” deals with claims that Princess Diana was murdered by the British establishment and the crime covered up.

An inquest held 10 years after Diana’s 1997 death in a Paris car crash deflated claims of a conspiracy, blaming her driver and pursuing vehicles.

But the movie by actor Keith Allen, father of singer Lily Allen, revisits the theories.

It has already been criticized in Britain for showing a picture of Diana after the crash. And its harsh criticisms of Britain’s “feudal” monarchy are sure to cause further furor.

The film was screened Friday on the fringes of the film festival for buyers and journalists.