The British Board of Film Classification (BBFC) surveyed more than 10,000 people and found it to be among parents' main concerns.

Any film showing sexual violence will now get at least a 15 rating rather than a 12 or a 12A.

The BBFC also wants its ratings to appear on all streaming services.

BBFC chief executive David Austin said a film like Keira Knightley's 2008 drama The Duchess, which was classed as a 12 at the time, would be made a 15 today because it included a rape scene.

"What parents told us was, that's too much for 12-year-olds," he told BBC News. "It's enough that a 12-year-old knows that a rape has taken place. They do not need to see it, no matter how discreetly it's filmed."

In the survey, parents said they were worried about the "sexualisation of society and what they called the pornification of society", according to Mr Austin.

"They are worried about children growing up being exposed to too much too soon, and they want to hold onto their children's childhood as far as they can," he said.

"That's another one of the reasons why from now on we will not be classifying any depiction of sexual violence at 12. We will limit it to 15."

The BBFC said they were right to give Netflix's To The Bone a 15 rating

The BBFC also looked at other "real life" scenarios like self-harm, mental health and suicide, but said its existing rules were in line with the public's views.

For example, viewers were happy that Netflix's To The Bone, about a young women dealing with anorexia, was given a 15.

"Parents and children said we were right to do this because that issue is not suitable when it's shown in that way for 12-year-olds," Mr Austin said.

Viewers were less worried about less realistic action violence, such as that seen in James Bond or Marvel films, the survey found.

Meanwhile, 95% of teenagers surveyed said they want online streaming services to carry the same age ratings as cinemas and DVDs.

They already appear on many Netflix shows and films, but Mr Austin said they were working with Netflix to make it 100% - as well as working with other services.

He said: "We are going to be working in 2019 with some of the big platforms to fulfil what the public has asked us to do, which is to ensure those ratings are consistent when you view something at the cinema, whether you view it on DVD or whether you view it on a tablet in your bedroom."

The new guidelines will come into effect on 28 February.

Films that would have a different rating

Red Sparrow would be an 18 if it was released under the new guidelines

• The Duchess - now would be 15 rather than 12A. The film contains a brief scene in which a man pushes a woman onto a bed and forces himself on her. The scene cuts away to outside the room but the actions implicate rape. Under the old guidelines this was considered permissible at 12A as the guidelines stated that sexual violence may be "briefly and discreetly indicated". However, the public were clear in the consultation that sexual violence should not be depicted at all at 12A and the new guidelines now prohibit this.
• The Kite Runner - now would be 15 rather than 12A. Similarly with The Duchess, The Kite Runner contains a scene with a rape implication. For the same reasons as above, the implicated actions would no longer permissible at 12A.
• 10 Cloverfield Lane - now would be 15 rather than 12A. Focus groups felt that the level of threat in the film was strong, rather than moderate, aggravated by the fact that the threat occurs within a realistic setting (at least until the sci-fi reveal later in the film). The threat also carries an element of sexual threat. The old guidelines permitted moderate physical and psychological threat at 12A but the new guidelines say any sexual threat must be brief and negatively presented.
• Sausage Party - now would be 18 rather than 15. Respondents to the research questions were surprised by the level of sexual detail throughout the film and considered that describing "strong sex references" was understated; suggesting "strong sexual themes" as a more accurate description.
• Wind River - now would be 18 rather than 15. Focus groups felt that the build-up of the sexual threat, combined with the gang nature and the recognisable 'real world' context were aggravating factors. The new guidelines state that sexual violence at 15 must not be detailed or prolonged and that credible real word settings and the presence of a gang dynamic are aggravating factors.
• Red Sparrow - now would be 18 rather than 15. Viewers did not feel enough had been cut from the film to classify it as a 15, and they particularly objected to the film's depiction of sexual violence and the way it combines sex and violence.