Image caption Lie detector tests are considered too unreliable for use in criminal trials in the UK

Mandatory polygraph testing for sex offenders is set to be rolled out across England and Wales following a successful pilot scheme, ministers say.

It found offenders who were tested were more honest and gave better information, which meant they were managed more effectively.

The pilot took place in the East and West Midlands probation areas from April 2009 to October 2011.

There are approximately 3,000 sex offenders on licence in the community.

Of these, 750 are considered to be in the most serious category of offender.

Prison recall

The government said it was now considering how the tests could best be used to manage offenders.

The pilot scheme found offenders using lie detectors made twice as many admissions to probation staff, for example admitting to contacting a victim or entering an exclusion zone.

Offenders also reported that the tests helped them to manage their own behaviour better

An offender can immediately be returned to prison if the lie detector tests and other information indicate they have broken their conditions or present a risk to public safety.

The government said the tests would be in addition to the rigorous conditions sex offenders face when they are released from prison, which includes signing the sex offenders register.

Truthful answers

A Downing Street source said: "It's vital that we protect the public from serious sex offenders. That's why the conditions after they leave prison need to be both strict and rigorously enforced.

"The pilot schemes using lie detectors to manage offenders in the community have been a success.

Lie detector tests can be an effective way of helping to manage and monitor the behaviour of sex offenders Jon Brown, NSPCC

"So now we're looking at how it could be rolled out to provide probation officers with more information to manage the most serious sex offenders."

Jon Brown, head of the National Society for the Prevention of Cruelty to Children's (NSPCC) sexual abuse programme, said: "Sex offenders should go to jail for their terrible crimes.

"But at some point they will be released and the findings of this pilot add to the increasing evidence that lie detector tests can be an effective way of helping to manage and monitor the behaviour of sex offenders in the community, including those who abuse children."

Polygraph tests, often referred to as lie detector tests, measure blood pressure, heart rate, breathing and levels of perspiration.

Experts use the tests to assess whether an individual is answering questions truthfully.