It would "open the floodgates to very unsuitable material appearing in schools for the use of children", she warned.

BBC: Peers urged to repeal Section 28

But parents might not be aware of other growing risks, such as their children finding unsuitable material on the internet.

BBC: Adventure playground

"Ending the exemptions from age classification for hard copy music videos will be an important step forward in making sure that children are not inadvertently exposed to unsuitable material, " said Mr Bailey.

BBC: Age-ratings call for music DVDs

Most Pixar films are rated G, though "Brave, " "Up, " and "The Incredibles" were rated PG, a signal that they might contain some material unsuitable for children.

WSJ: 'Monsters University' Teaches Pixar About Prequels

Ofcom found Channel 4 in breach of rule 1.3 of the broadcasting code, which states children must be protected by appropriate scheduling from material that is unsuitable for them.

BBC: Hugh Jackman in Wolverine

Universal said it had not been broadcast at unsuitable times, and did not contain any contentious material.

BBC: Jolie gun film advert is banned