A review of how sex offenders are dealt with is currently being conducted by the Home Office.

Stung by criticism after a string of high profile paedophile cases, the government is looking at existing sentencing and supervision laws, and a White Paper is due out in the spring.

One proposal being considered is handing down indeterminate jail sentences to dangerous sex offenders.

It is a measure which is endorsed by child protection bodies like the NSPCC.

For the highest risk offenders, indeterminate sentences is the only way to keep children safe

Mary Marsh NSPCC

The children's charity argues that some convicted sex offenders are untreatable and are likely to seek out and abuse other youngsters on release.

It is calling for courts to be given the power to leave the length of sentence open at the time of conviction of these offenders, while they continue to pose a threat to children.

Director Mary Marsh said: "For the highest risk offenders, indeterminate sentences is the only way to keep children safe."

Reviewable sentence

Another way to build in controls to the length of time a paedophile spends in jail would be to make their sentence reviewable.

So while they continued to be a danger to society - or refuse treatment like Roy Whiting - they would be kept locked up.

Nacro, the crime reduction charity, says the measure would be available to the courts as a way of dealing with cases in which it was clear the offender was still dangerous, but where a life sentence was not appropriate.

"The devastating effects of sexual offences on victims can justify very substantial restrictions on the liberties of sex offenders," said Paul Cavadino, Nacro's director of policy.

Public access to details about known sex offenders would not have saved Sarah Payne

Paul Cavadino Nacro

"The best way of protecting children from known and dangerous paedophiles is to ensure that they are not released from prison if they still pose a genuine risk."

Nacro rejects giving the parents access to the Sex Offenders' Register in the form of Sarah's Law, being put forward by the parents of murdered schoolgirl Sarah Payne.

"Public access to details about known sex offenders would not have saved Sarah Payne," said Mr Cavadino.

"A reviewable sentence and extended supervision might have done."

As part of its review, the Home Office is also looking at the controversial issue of informing a jury if a defendant has previous convictions for similar crimes.

Prejudicial evidence

The Law Commission, which recommends legal reforms to the government, has published a report which said that prejudicial evidence should be admissible "if it is relevant to a specific issue in the case".

That would mean in the Sarah Payne case, details of Whiting's conviction for kidnapping a young girl in eerily similar circumstances six years before would be disclosed to the jury.

There has been a raft of new laws aimed at giving better protection to children in the past few years, including the Criminal Justice and Court Service Act which was implemented in June 2001.

Under it, courts can issue specific orders stopping offenders from contacting their victims or travelling abroad without telling police.

The way forward is to impose an adequate form of control on their behaviour

Harry Fletcher Probation officer

And some experts argue that the first issue to be tackled is rather than making new laws, ensure the ones that exist are used fully by the courts.

Nacro would like more judges to make use of extended supervision orders which would mean the offender's movements are strictly curtailed for up to 10 years.

Harry Fletcher, assistant general secretary of the National Association of Probation Officers (Napo), believes a stricter use of curfews, electronic tagging, reporting to police and probation officers and even lie-detector tests would make a vast difference in preventing re-offending.

"But that's expensive," he said.

"The way forward is to impose an adequate form of control on their behaviour but the government has got to resource it properly."