The British Board of Film Classification (BBFC) say 18-category films will be cut "only rarely" - when "the more explicit images of sexual activity" cannot be justified by context, or scenes "promote" violent or dangerous acts including drug use.

However, the rules for what can be shown to younger viewers will be tightened up, particularly regarding the portrayal of drug use.

The first sign of the censorship thaw came on Thursday when one of the world's most notorious sex films, Deep Throat, was finally passed uncut by the BBFC.

The movie caused outrage when it was made in 1972 for its graphic scenes and the film is widely credited with breaking down US censorship laws.

BBFC Director, Robin Duval, said on Thursday: "What was very clear from the consultation - which involved over 3,000 people from all demographic groups and from right across the UK - was that adults want to choose what they watch without excessive intervention by the board."

The BBFC decided to tighten its rules on the portrayal of drug use, violence, bad language and sex in films and videos aimed at young people after its survey revealed most people wanted more protection for children.

It is also going to be stricter on blasphemy after the survey highlighted intolerance of swearing with religious associations.