The mother of murdered schoolgirl Sarah Payne today warned peers not to wreck a Government crackdown on sex offenders.

The Sex Offences Bill is facing a tight deadline to become law before the current Parliamentary session ends on Thursday.

Sara Payne, whose eight-year-old daughter was snatched from a field in West Sussex and murdered by paedophile Roy Whiting, fears a row between MPs and the House of Lords could lead to the legislation being shelved.

The Bill tightens up sex offender register loopholes, forcing perverts to notify police of a new address in three days instead of two weeks. It also makes internet "grooming" an offence.

Tory and Liberal Democrat peers have tabled an amendment which would force police to apply to a court to identify anyone accused of a sex offence.

But MPs are certain to reject the move, leaving peers with a difficult choice of backing down or pushing the issue and the Bill being dropped.

Sara, who has campaigned for the law to be tightened since her daughter's death in July 2000, said: "I would be outraged if this Bill was lost because of this amendment, especially as it is something that puts suspects before victims.

"If peers are so keen on changing the law they should introduce their own Bill and not try to hijack the one we have spent so long working for."

Home Secretary David Blunkett has described the amendment as unworkable.

He said the time wasted applying to the courts for permission to identify a suspected sex offender could put children in "real danger".

But Shadow Home Secretary David Davis said: "To drop such an important Bill because the Government failed to win one vote is ludicrous.

"This Bill implements a great number of Conservative proposals which would do a lot to protect children."

Whiting, 43, from Littlehampton, is serving life for Sarah's murder.

He abducted the youngster as she played near her grandparents' house in Kingston Gorse, near Ferring. Her body was found 16 days later near Pulborough.