Lie detector technology is already used to root out benefit cheats
Sex offenders in some parts of England and Wales could be made to take compulsory lie detector tests to see if they are still a danger to the public.
The Ministry of Justice said a pilot scheme would test the use of polygraphs for offenders living in the community.
Results could affect how they are monitored, but the results will not be admissible as evidence in court.
An earlier voluntary pilot found that nearly 80% of lie detector tests prompted admissions from offenders.
Each test will last for about 90 minutes and will monitor a subject's heart rate, sweating, brain activity and blood pressure while he or she is asked questions.
In previous pilots, 90% of probation officers said the testing of offenders was helpful in assessing the risks they pose to the public.
It was found that offenders were more likely to disclose information relevant to their behaviour and treatment when challenged with the results of their tests.
Where tests were voluntary, fewer than half of those eligible agreed to take part.
But under the new scheme, paedophiles and other sex offenders will have no choice but to comply.
Children's charity Barnardo's welcomed the move.
Chief executive Martin Narey said: "This has the potential to increase public confidence that sex offenders are complying with supervision, that they are staying away from schools and playgrounds and living and sleeping where they are supposed to.
"Sex offenders trying to avoid re-offending will be helped by the knowledge that polygraph testing will expose any attempt by them to mislead their probation officer.
"All in all, this will make our children safer."
A consultation document on the rules of the programme was published by the Ministry of Justice on Friday.
The locations for the three-year-pilot, which will begin in April 2009, have not yet been formally chosen, but a spokesman said they were likely to be in the east of England and West Midlands.
If successful, the scheme could be extended across the country.
Telephone lie detectors, which use so-called voice-risk analyser technology, are increasingly being used by councils to identify potential benefit cheats.