The Home Office faces renewed criticism today after a tabloid newspaper accused it of losing track of 322 sex offenders.
The Metropolitan police do not know where 88 offenders are and the West Midlands police force have lost track of 25, the News of the World claims.
Other forces with missing sex offenders include Greater Manchester police, who do not know the location of 18 convicts, Hampshire, with 11 missing, and Northumbria, who have lost track of ten.
Under the Freedom of Information Act, the newspaper's investigators asked all 50 police forces in England, Wales, Scotland and Northern Ireland how many sex offenders had managed to escape police tracking and monitoring.
Current legislation states that convicted criminals subject to the sex offenders register will go to jail if they fail to inform the police of changes to their address or name.
Only two Welsh police forces failed to give figures, Dyfed Powys and Gwent, and none of the forces said how long the offenders had been missing for. They also refused to detail how many of the offenders are paedophiles.
According to the investigation, such criminals can escape police tracking by giving the police a vague address. The newspaper points to one case of a convicted paedophile giving his address "a tent near Guildford leisure centre" before moving to "woods".
Michele Elliott from child protection charity Kidscape warned: "It's totally unacceptable for registered sex offenders to be missing."
But Tony Blair backed the Home Office. Although admitting in an interview to the BBC that "of course there's been huge problems in the Home Office", the prime minister said that many of these issues were emerging because of a desire to reform and improve.
"Some of these things like foreign prisoners, all of these offences being committed abroad by British people who are then returned back home, the reason we're dealing with these is that for the first time there is a process in place for dealing with them," he said.
"You measure authority by getting things done. The very things we've got a lot of these issues on our plate is precisely because we are pushing things forward."
Today's report will embarrass home secretary John Reid further. In the past two weeks, the Home Office has been chastised for failing to update records with crimes committed by Britons abroad and telling courts to only send the most dangerous criminals to prison due to the overcrowding in prisons.