A cinema audience of children waiting to view the hit Disney animation Frozen were accidentally shown a trailer for explicit art house sex epic Nymphomaniac.

Parents in the auditorium in Tampa, Florida, reportedly struggled to cover the eyes of their offspring, while others headed swiftly for the exits, as an apparent technical error saw the promotional clip for Danish agent provocateur Lars von Trier's salacious new film suddenly hit the big screen.

"They put in the filler, it looked like Steamboat Willie, the old Mickey Mouse cartoon, and then all of a sudden it goes into this other scene," grandmother Lynn Greene told My Fox Tampa Bay. "It seemed like forever when you're trying to, you know, 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.

"You're talking, what, a PG-rated movie to all of a sudden have an R-rated scene up there for little children?" she added. "My concern is that there should be safeguards in place so that this doesn't happen again."

The trailer has been described by Vanity Fair as one of the most explicit ever to be shown in mainstream cinemas. A teaser trailer was briefly removed from YouTube last month after apparently falling foul of the site's rules on nudity and sexual content. Von Trier's much-hyped film, which features Uma Thurman, Stellan Skarsgård, Christian Slater, Jamie Bell and Shia LaBeouf, will use digital trickery and body doubles to portray its famous stars having sex. It is due to premiere in Copenhagen on Christmas Day and is then likely to hit the festival circuit, with a possible appearance at Cannes in May.

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