Online pornography showing strangulation or suffocation is to be made illegal, as part of government plans to tackle violence against women and girls.

It follows a review which found depictions of choking were "rife" on mainstream porn sites and had helped normalise the act among young people.

Both the possession and publication of such material will be a criminal offence, under amendments to the Crime and Policing Bill currently going through Parliament.

Online platforms would also be required to proactively detect and remove such material or face enforcement action via media regulator Ofcom.

The Department for Science, Innovation and Technology (DSIT) said the change would make choking in pornography a "priority offence" under the Online Safety Act, putting it on the same level as child sexual abuse material and terrorism content.

Technology Secretary Liz Kendall said: "Viewing and sharing this kind of material online is not only deeply distressing, it is vile and dangerous. Those who post or promote such content are contributing to a culture of violence and abuse that has no place in our society.

Conservative peer Baroness Bertin warned earlier this year that there has been a "total absence of government scrutiny" of the pornography industry.

Her independent review, published in February, cited an account of a 14-year-old boy asking a teacher how to choke girls during sex and warned that people imitating such behaviour "may face devastating consequences".

Speaking to the Today programme, on BBC Radio Four, Baroness Bertin welcomed the government's move but said more action was needed.

"It's only the beginning as there's still so much violent pornography that is completely legal in the online world and completely illegal in the offline world," she said.

"The government has to use this as a first step to try to address that balance."

'Serious form of violence'

A BBC survey carried out in 2019 suggested 38% of women aged 18-39 had been choked during sex.

Bernie Ryan, chief executive of the Institute for Addressing Strangulation, welcomed the government's amendment, saying choking can send "confusing and harmful messages" to women about what to expect in intimate relationships.

"Strangulation is a serious form of violence, often used in domestic abuse to control, silence or terrify," she said.

Andrea Simon, director of the End Violence Against Women Coalition, described the amendments as "a vital step" towards tackling the normalisation of violence in online content.

"There is no such thing as safe strangulation; women cannot consent to the long-term harm it can cause, including impaired cognitive functioning and memory," she said.

"Its widespread portrayal in porn is fuelling dangerous behaviours, particularly among young people."

But campaigner Fiona Mackenzie, founder of the group We Can't Consent To This, was less optimistic of the proposed law's effectiveness.

She argued there were already existing laws against showing choking in pornography, but which were not enforced in practice.

This included the Criminal Justice and Immigration Act 2008, which criminalises the possession of extreme porn, including that showing life-threatening acts.

"More than five years ago, young women told us that social media sold strangulation of women as normal, as an expression of passion," she said.

"The porn sites make this normal for men - and none of those sites have ever felt the impact of the existing law.

"So, a change in law or practice is needed. It's possible that this time the government might actually do something about this.

"However, until we see otherwise, I don't believe that any new law will actually be enforced."

The government said in June, when the amendment was pledged, that it built on existing laws, including the Obscene Publications Act 1959 and the Criminal Justice and Immigration Act 2008. (BBC)