A suspected serial rapist may have been mistakenly released from prison, it has emerged.
An urgent review has been launched amid fears that Joseph McCann, who is wanted over the abduction and rape of two women and suspected of also snatching a third, was set free due to an error.
McCann, 34, is being hunted by police over the abduction of two women in their 20s who were separately snatched off the streets in north London last Thursday.
He is also suspected of snatching a 21-year-old woman at knifepoint in Watford in the early hours of April 21 and raping her, Hertfordshire Police said.
Police have offered a reward of up to £20,000 for information leading to McCann’s arrest and prosecution.
It is understood that McCann was released from prison on life-long licence in February 2017 after serving 10 years of a sentence for an aggravated burglary.
The sentence was an Indeterminate Sentence for Public Protection (IPP) which meant the Parole Board had to decide if it was safe to release him once his tariff expired in 2010.
After his release in 2017 he was jailed again for theft and burglary but is believed to have been mistakenly released automatically half-way through the three-year sentence, when it should have been up to the Parole Board to decide.
A Ministry of Justice spokesman said: "We have commissioned an urgent review into what happened in this case."
Police have warned that McCann is "extremely dangerous", known to use false names and may be using a disguise.
He is described as muscular, about 5ft 10in, with a “slight” Irish accent and a "distinctive" tattoo of the name "bobbie" on his stomach.
Officers said he had recently used the name Joel and has links to Watford, north-west London, Aylesbury in Buckinghamshire, and Ipswich in Suffolk.
The women abducted in London - one of whom reportedly may have been pregnant - were raped after being snatched by a man in a silver or grey Ford S-Max people carrier with false registration plates.
The first woman was abducted at about 12.30am on Thursday from a street in Chingford, before the second was seized around 12 hours later at 12.15pm from a street in Edgware.
They were driven to a hotel where the man tried to book a room at around 1pm but after leaving because it was unavailable they later managed to escape in Osborne Road, Watford at about 2.30pm.
The incident is being linked to another attack in Watford earlier in the week.
Hertfordshire Police said a woman was approached at around 3.30am on April 21 in Hagden Lane, Watford, driven around for six hours in a blue Ford Mondeo and then raped.
The force named McCann on its Facebook page on Thursday as being wanted on recall to prison without mentioning the rape.
A spokesman said: "He was named as wanted on recall to prison on our Facebook page on Thursday April 25. This is a complex inquiry and we were actively pursuing numerous, significant lines of inquiry throughout the week in order to trace and arrest the suspect.
"It is normally only when we have exhausted those inquiries do we put out a wanted appeal. We are continuing in our efforts to trace him and we are working closely with the Metropolitan Police Service."
On Tuesday, a 63-year-old woman from Aylesbury was arrested on suspicion of intimidation of witnesses in connection with the attack and released on bail.
A 33-year-old man arrested on Sunday on suspicion of conspiracy to rape has been released under investigation.