The UK government is facing calls to drop its proposed ban on pornography featuring bondage and sadomasochism (BDSM).

New proposals contained in the Criminal Justice and Immigration Bill would make it a crime to view any image classed as "extreme".

This would include "an act which results in or appears to result (or be likely to result) in serious injury to a person's anus, breasts or genitals".

The new proposals were inspired by the murder of special needs teacher Jane Longhurst by Graham Coutts, who was a regular viewer of such images.

Longhurst's former partner, Malcolm Sentence, told the BBC at the time of the murder that Longhurst "would still be here if it wasn't for the internet ".

Following Coutts's conviction, Longhurst's mother organised a petition to ban such images. It was signed by 50,000 people.

But pressure group Backlash, which includes the Libertarian Alliance, the Spanner Trust, the Sexual Freedom Coalition, Feminists Against Censorship, Ofwatch and Unfettered, has condemned the legislation and called for its withdrawal.

"Much has been made of the 50,000 who signed the petition organised by [Labour MP] Martin Salter and the Jane Longhurst Trust," said the group in a statement.

"But the wording of the petition invites signatories to oppose 'extreme internet sites promoting violence against women in the name of sexual gratification'.

"Anyone would object to material 'promoting' violence against women, but the scope of the legislation is much wider than this. It criminalises material featuring consenting adults engaging in staged or controlled fantasies."

Backlash warned that the proposed legislation would hit BDSM groups, Goths and many horror or thriller films that "convey a realistic impression of fear, violence and harm".

"No-one is stopping people doing weird stuff to each other but they are strongly advised not to put it on the internet," said Salter, who has been involved in writing the legislation. "It is all too easy for this stuff to trigger an unbalanced mind."

But this assertion has been disputed by scientists, who claim that it is just another example of a moral panic.

"The current fears around the possible impact of 'violent pornography' on the internet seem very similar to previous 'moral panics' from penny dreadfuls in Victorian times, to horror comics in the 1950s, to video nasties in the 1980s," said Dr Megan Barker, senior lecturer in psychology at London's South Bank University.

"Time and time again research has challenged the simple cause-effect relationship between exposure to such media and violent behaviour.

"But it is an easy scapegoat in a society which does not want to look at the more complex and insidious reasons for crime and violence, for example issues around poverty, class and the kinds of gender roles that are valued."