Officers will not disclose the identities of some 800 sex offenders and paedophiles who have changed their names by deed poll to disguise their criminal pasts.

Their refusal means young families have no way of knowing whether or not their are predatory paedophiles living in their communities.

Child abuse campaigners reacted with fury to the revelations, with one saying: “Parents must be able to find out if there is a threat to the community.”

People on the sex offenders register must inform police within three days if they decide to use a a new name, and face five years in prison if they fail to do so.

Figures obtained following a Freedom of Information (FOI) request by The Sun show that 803 sex offenders have changed their names in the last five years.

Of these, there were 83 rapists, 126 offenders who had possessed or distributed child abuse images, 88 people convicted of indecent assault, and 44 convicted of sexual assault.

However, two police forces have insisted that publishing the perverts’ new names would breach their human rights or data protection rules.

One of those to exploit the loophole was hospital DJ Matt Richards, who changed his name from Andrew Watt before beginning a year-long campaign to worm his way into an unsuspecting family in order to get closer to their young child.

The 46-year-old’s “manipulative” methods were only uncovered when the mother found out his real name and Googled it, which brought up newspaper articles detailing to his sordid criminal past.

Richards was on licence after serving a prison sentence for sex offences against a 15-year-old girl in 2003.

He was sent back to jail for 33 months in June for breaching the terms of his release.

The force with the highest number of name changes was Nottinghamshire Police, with 149 and only 18 out of the country’s 45 forces responded to the request, meaning the true toll could be much higher than the 803 registered.

That figure is also likely to be a vast underestimate because a number of criminals could be ignoring the law and using new identities the police know nothing about.

Three of the country’s biggest forces, the Metropolitan Police, Greater Manchester Police and West Midlands Police said it would be too expensive for them to reveal the information, according to The Sun. Merseyside Police and Dyfed Powys Police said giving further details of the offenders would put their human rights at risk, the paper claimed.