Instead film bosses are focussing on CGI action scenes and special effects to entertain audiences, according to a report in the Sunday Times.

And analysts say the last major blockbuster to include an extended sex scene was Titanic - made in 1997.

The James Cameron smash showed Leonardo DiCaprio and Kate Winslet getting it on in a car.

Studios are now demanding script writers and directors create films that are more "family friendly" so they have a better chance at the box office.

Industry experts predict memorable scenes such as when Sharon Stone exposed herself in Basic Instinct would not be made in the current climate.

Film research expert Vincent Bruzzese said: "Sex scenes used to be written, no matter the plot, to spice up a trailer. But all that does today is get a film an adult-only rating and lose a younger audience.

"Today such scenes are written out by producers even before they are shot.

"They ask: do we really need the sex? Can we fill the space with dazzling special effects instead and keep the family rating."

Bruzzese said Oscar winner Jennifer Lawrence's role in Silver Linings Playbook was typical for the modern era.

He told how the brunette beauty won the Best Actress gong for her portrayal of a sex addict - without one sex scene in the entire movie.

A decade ago 120 films given an "R" rating broke into the US box office top 10. Last year there were only 80.

And the report says most of these movies were certified "R" - equivalent to a 15 over here - because of violence and not sex.

Paul Degarabedian from Hollywood.com said there was more sex available on the internet and TV than at the cinema.

He said: "It's not like the 1970s when young directors reflected the sexual revolution and films such as Last Tango in Paris could cross over to become a mainstream hit.

"If the sexually explicit scenes on TV shows such as Girls were made for cinema, they would not get a certificate."

However, a movie version of "mummy porn" book 50 Shades of Grey is planned for release next year.