A move to train probation officers to become "lie detector examiners" and introduce satellite tagging has been welcomed by Devon and Cornwall's police and crime commissioner Tony Hogg, despite evidence that polygraphy is unreliable, unscientific and biased.

Sex offenders on licence will now face some of the world’s toughest approaches to supervision, according to the Justice Minister, Jeremy Wright.

Probation officers have begun training to become polygraph examiners, putting some of the most serious sex offenders in the community under "stringent tests" according to the minister. Around 1,000 will undergo the compulsory lie detector tests "designed to make sure they are sticking to their licence conditions".

However the scientific community has differing views on the accuracy of polygraphy. The National Research Council in the USA says that its use among sex offenders is poor, with insufficient evidence to support accuracy or improved outcomes.

The National Academy of Sciences in the USA, has said that the idea of valid detection of truth or falsehood through measuring respiratory rate, blood volume, pulse rate and galvanic skin response is a "mere pretense". Adding that psychologists cannot ascertain what emotions one has, with or without the use of polygraph.

Polygraphs measure arousal, which can be caused by anxiety, anxiety disorders such as PTSD, nervousness, fear, confusion, hypoglycemia, psychosis, depression, substance induced (nicotine, stimulants), substance withdrawal state (alcohol withdrawal) or other emotions; polygraphs do not measure "lies". 

Steps can also be taken to 'fool' the tester and the equipment. With numerous famous cases where Soviet spies and criminals passed numerous lie detector tests. There are also a large number of cases where innocent people have 'failed' lie detector tests.

A polygraph cannot differentiate anxiety caused by dishonesty and anxiety caused by something else.

Despite the dispute over its validity, Mr Hogg has called it "an important step forward".

He added: "We must make full use of all the tools at our disposal to address this issue and ensure that offenders are conforming. Probation officers have a vital part to play in this, and i'm pleased that this comprehensive training is underway, and will have a major impact."

The lie detector is the latest in a series of plans to tighten up controls on sex offenders, which will also see their every movement tracked by satellite tags, when the technology is available. Libido suppressant drugs can also be prescribed to further reduce the risk posed by this group of offenders.

The polygraph training is being delivered by Behavioural Measures, led by Don Grubin, Professor of Forensic Psychiatry at Newcastle University. Probation officers from the new National Probation Service (NPS) are undertaking the 12 week training programme to qualify as Polygraph Examiners.

Jeremy Wright said: "This government is introducing lie detector tests for high risk sexual offenders, as well as satellite tagging to track their movements."

"We are determined that the UK has one of the toughest regimes in the world for managing sex offenders, to stop reoffending and to protect victims."

Compulsory lie detector testing will start from October 2014, once the training has been completed.

This testing will be in addition to existing licence conditions which can include, signing the sex offender register, exclusion zones, non-contact orders, curfews, internet restrictions and compliance with sex offender treatment programmes. Offenders will be required to take the test every six months and, if "found to have been covering up inappropriate behaviour", they are likely to be recalled to prison.

On the examinations, Professor Don Grubin said: "Polygraph tests can be an important tool in the management of sex offenders and can enhance provisions already in place."

Previous studies have shown that polygraph testing both facilitates the disclosure of information and alerts offender managers to possible deception, allowing them to work with offenders in a more focused way.

Under the reforms to transform rehabilitation, the NPS will be tasked with supervising more than 37,000 sexual and violent offenders.