PARIS - Monaco's Prince Albert and his two sisters said a new film in which Nicole Kidman plays their late mother, actress Grace Kelly, later Princess Grace, was a "farce" that bore no relation to reality.

Albert, monarch of the tiny Mediterranean principality, and his sisters, Princess Caroline and Princess Stephanie, said Grace of Monaco was based on "erroneous and dubious historical references."

The film was originally slated for cinema release in November but is now set to open at the Cannes Film Festival on May 14.

"The trailer appears to be a farce and confirms the totally fictional nature of this film," the Monaco royals said in a joint statement. "The princely family does not in any way wish to be associated with this film, which reflects no reality, and regrets that its history has been misappropriated for purely commercial purposes."

Kelly, star of such Hollywood classics as To Catch a Thief and High Society as well as Alfred Hitchcock's Rear Window and Dial M for Murder, became Princess Grace when she married Albert's father, Prince Rainier of Monaco, in 1956. Rainier is played by British actor Tim Roth in the film.

Grace died in a car crash in 1982. Albert ascended the throne after Rainier's death in 2005.

In their statement, the royals said director Olivier Dahan and the producers had refused to take into account observations the palace made that "called into question the entire script and the characters of the film."

Hollywood trade magazine Variety reported this week that producer Harvey Weinstein was considering dropping U.S. distribution rights to the film after being unsatisfied with the latest version.