The family of a schoolgirl who was sexually assaulted and murdered has launched a campaign for a change in the law.

Relatives want first-time child sex attackers jailed for life, with the emphasis placed on them to prove they no longer pose a risk of reoffending before they can be released.

Roy Whiting was jailed for four years in 1995 for assaulting a young girl and is now serving life for murdering Sarah Payne after his release.

Nigel Heffron, uncle of a murdered nine-year-old girl, is in no doubt Sarah would be alive if Whiting had been jailed for life for his first offence.

Mr Heffron's niece Nicola Fellows and her playmate Karen Hadaway, both nine, were strangled in Wild Park, Brighton, in 1986.

Brighton roofer Russell Bishop was cleared of the murders at Lewes Crown Court but was later jailed for life for the attempted murder of another girl at Devil's Dyke.

No one has been brought to justice for what became known as the Babes in the Wood attacks.

Bishop contacted police during the Sarah Payne inquiry saying Whiting was responsible for the Wild Park murders. They took no action.

Mr Heffron, who lives in Brighton, is urging people to lobby MPs for the change in the law.

He said: "If MPs refuse, we should name and shame them. This switch in emphasis is essential to protect our children."

Mr Heffron, backed by Nicola's mother Susan, opposes the call by Sarah's parents for legislation allowing people controlled access to information about paedophiles living in their area.

He said it would drive paedophiles underground and could lead to attacks by vigilantes.

He said: "This new idea would put first-time child sex offenders behind bars indefinitely and until it is proven they no longer pose a threat to children."

Also opposed to the so-called Sarah's Law is Detective Inspector Ivor John, in charge of monitoring sex offenders in Brighton and Hove.

All 200 on the list regularly report to and are reviewed by the police, social services, housing, probation and mental health services, he said.

A report suggesting there were more than 500 dangerous sex offenders in the city was dismissed.

Mr John said there were about ten who were on the "critical few" list and they were closely monitored.