Police around the country have lost track of 322 convicted sex offenders, it was reported.
The offenders have managed to give police forces across Britain the slip, the News of the World revealed.
The revelation will come as a fresh blow to Home Secretary John Reid whose department is already under fire for failing to carry out proper checks on thousands of British criminals convicted abroad and for failing to enforce travel bans on 150 drug traffickers.
The newspaper requested the information from all 50 police forces across England, Wales, Scotland and Northern Ireland under the Freedom of Information Act. Freed sex offenders are supposed to be monitored by officials working under Multi-Agency Public Protection Arrangements (MAPPA).
But according to the paper, registered sex offenders, including rapists and paedophiles, have used a loophole in the system allowing them to register vague addresses in order to disappear.
Last year one paedophile who breached register conditions was allowed to give his address as "woods" after moving from "a tent near Guilford leisure centre", the paper claimed.
The investigation revealed the Metropolitan Police had lost track of the whereabouts of 88 sex offenders - the highest number of any force. West Midlands Police had lost 25 and in Greater Manchester the number stood at 18. Cambridgeshire, Cheshire, Durham and Norfolk Police said they had no missing sex offenders in their area.
The Home Office said the UK has one of the most advanced systems in the world for monitoring dangerous offenders. A spokesman said: "The day-to-day management of sex offenders on the register is rightly a matter for the police and probation services.
"Where an offender appears in breach of their notification requirements the police will update the Police National Computer and the Sex Offender Register to ensure they are traced and dealt with appropriately.
"The sex offenders register is a powerful operational tool for managing sex offenders in the community with a compliance rate of 97% for those subject to its requirements. In the UK we have one of the most advanced systems in the world for monitoring and managing dangerous offenders. The Government is committed to protecting the public and is determined to strengthen arrangements for dealing with sex offenders in the community."
