A Florida cinema angered parents after playing a sexually explicit film clip before screening Disney's new cartoon movie.

Children and parents who had gone to see Frozen at the Regal Cinemas' Park Place Stadium 16 in Pinellas Park were instead subjected to an X-rated trailer for Nymphomaniac.

According to WTVT-TV, parents covered their children's eyes and ears when the trailer promoting controverisal director Lars Von Trier's picture came on. Scenes focused on a number of sex acts and violence.

Grandmother Lynn Greene said that she struggled to shield her grandchildren once she realised the pornographic content.

"It seemed like forever when you're trying to cover a little guy's eyes. I didn't have enough hands to cover his ears too - and he got the sound down real good," she said.

The cinema's general manager apologised to moviegoers and offered those who were in the audience free movie tickets. He blamed a technical hitch.

Some sceptical parents, however, blamed the problem on the pranks of "an immature teenage" who was imitating a character from the film Fight Club who spliced explicit imagery into family films while working as a cinema projectionist.

"Inserting a sex scene into a movie for kids sounds like a progressive democrat at work to me!" one viewer said.

In 2012, a cinema in Nottingham screened horror movie Paranormal Activity 4 to an audience who had gone to see kid-friendly animation Madagascar 3.

Frozen will open in UK cinemas on Friday (6 December).