Leaders of the G8 group of the world's richest nations are to consider banning violent internet porn in the wake of the murder of Brighton teacher Jane Longhurst.

The breakthrough is the biggest boost yet to a campaign launched by Miss Longhurst's 73-year-old mother Liz.

Her year-long crusade - supported by The Argus - has already received backing from the US Attorney General's department and is gathering momentum by the day.

Amnesty International today put its weight behind the effort and demanded the "disgusting" images - downloaded in their thousands by Miss Longhurst's killer - be wiped off the internet.

Home Secretary Charles Clarke this week pledged a crackdown. He told Brighton MP David Lepper: "I am absolutely committed to seeing action this year."

Mr Lepper and Mrs Longhurst met Mr Clarke this week and the Brighton MP said afterwards: "This issue will be taken up with our European partners during the UK's presidency of the G8 this year."

Mr Lepper revealed Home Office researchers already were looking for ways of outlawing violent sex sites.

He said: "With the US Attorney General and other countries showing support I am more confident than ever the campaign will succeed."

Mrs Longhurst, who has been working tirelessly for a ban as a lasting memorial to her daughter, was delighted but remained as determined as ever.

She said: "Mr Clarke assured us he would be proactive on this and said he was keen we should continue prodding him about this."

Mrs Longhurst welcomed Amnesty International's decision to join the effort.

An Amnesty spokesman said: "We believe such material constitutes a direct incitement to commit violence against women and poses a threat to women."

Amnesty is running a campaign called Stop Violence Against Women to stamp out all forms of such violence.

The spokesman said: "We support Mrs Longhurst's campaign to make the possession of violent pornography illegal.

"These disgusting images, which include the choking, assault and torture of women, encourage violence against women and pose a threat to women's safety.

"We hope the Government will listen to what Mrs Longhurst and her family have to say and act to control the availability of this material."

Graham Coutts, who murdered Miss Longhurst to satisfy perverted sexual fantasies, downloaded thousands of images of necrophilia and strangulation sex before and after throttling her with a pair of tights.

Mrs Longhurst announced her nationwide campaign on the day of Coutts's conviction last February.

She insisted the web sites should be classified like child pornography and outlawed.

Mr Lepper said a ban would need international agreements and would involve internet service providers and credit card companies.

He warned it could still take some time but was convinced Mrs Longhurst's "valiant" cause would win the day.

He promised: "We will not let this issue slip on to the back-burner."

Hundreds of Argus readers signed Mrs Longhurst's petition, which now has more than 30,000 names.

They put pen to paper after Coutts, 35, of Waterloo Street, Hove, was jailed for life for murdering Miss Longhurst, 31, and keeping her body in a storage unit which he visited nine times.

Miss Longhurst's burnt body was found on Wiggonholt Common, near Pulborough, in April 2003.

Coutts lost an appeal against conviction and will have to serve at least 26 years.