Convicted paedophiles would face mandatory lie detector tests in parts of the UK under plans put forward by the government.
The use of polygraph tests has been piloted in part of the UK
The measure is in the Management of Offenders and Sentencing Bill, which was published on Thursday.
The Home Office says 148 tests have been carried out on sex offenders since a pilot scheme began in September 2003.
The bill also contains plans to allow private companies to supervise offenders on community sentences.
The use of lie detector - or polygraph - tests has been piloted in areas across the UK, including Lancashire, Manchester, Devon and London, on volunteers.
Under the proposals, the tests would become mandatory in the pilot areas.
POLYGRAPH PILOT AREAS
Leicestershire and Rutland
Devon and Cornwall
Bedfordshire, Hertfordshire and Cambridgeshire
They could be used to help monitor behaviour, such as whether sex offenders are keeping bail conditions to stay away from schools.
The Home Office will see how the tests work in the pilot areas before deciding whether to use them nationwide.
A spokeswoman said: "Protecting the public is our priority. We have a responsibility to keep abreast of modern technological developments to see how they can help us."
Some groups oppose the use of polygraph tests because they do not think the equipment used is reliable.
The Conservatives have criticised another measure in the bill, which is designed to make judges more aware of the space available in prisons when sentencing criminals.
The government says law-breakers should be given "effective punishments" but prison should be "reserved for the most dangerous and persistent offenders".
But Shadow Home Secretary David Davis said the measure showed the government's prison policy had failed.
He added: "Those who deserve to be in prison should be in prison. Sentencing should be determined by the crime, not by the number of prison places available."
Other measures in the bill include allowing private companies and volunteers to supervise offenders on community sentences - allowing them to compete with the public sector.
But Liberal Democrat home affairs spokesman Mark Oaten said "increased privatisation" and a major re-organisation of the prison and probations services was not likely to be effective.
"The government must tackle the appallingly high rates of re-offending by ex-prisoners first," he said.
Details of the bill were first revealed in the Queen's Speech last November.