Police and probation services are watching 2,158 sex offenders in the West Midlands, the Home Office has revealed.
Last year, 28 sex offenders in the area were sent back to jail or jailed for the first time, because they broke the terms of their licence.
The figures were revealed in a Home Office report last night.
The offenders have all been added to an official list of people who can never be allowed to work with children.
But the charity the NSPCC has warned police and probation services need more resources to ensure youngsters are protected.
Sex offenders in England and Wales are subjected to strict licence conditions on release from prison, and can be sent back to jail if they fail to co-operate.
Last year, 76 offenders in the region were locked up because they breached the conditions, including 28 in the West Midlands Police area, 22 in Staffordshire, 16 in the West Mercia Police area and ten in Warwickshire.
According to the Home Office, more sex offenders live in the West Midlands area than other parts of the country, even taking into account a high population.
The total of 2,158 offenders amounts to 82 offenders per 100,000 people.
But in Staffordshire, there are only 538 sex offenders, or 51 per 100,000 people.
In the area covered by West Mercia Police, including Worcestershire, Herefordshire and Shropshire, there are 689 sex offenders, or 60 per 100,000 people.
And in Warwickshire there are just 231, or 45 per 100,000 people.
The West Midlands also has more sex offenders than similar urban areas. For example, Merseyside has a total of 941 sex offenders, or 67 per 100,000 people.
The Home Office said sex offenders were "tightly managed. But the NSPCC said all sex offenders should be subject to the same level of stringent surveillance currently used to keep track of the most dangerous.
Wes Kewell, the charity's director of services for children, said: "If you're a medium-risk offender you'll be expected to report from time to time, but otherwise, basically, you will be left to get on with it, with severe warnings about your conduct."
Sex offenders are monitored by police, probation services and prison services, working together through a body called Multi-Agency Public Protection Arrangements (MAPPA).
Last night Home Office Minister Baroness Scotland said the high number of offenders sent back to prison was proof the arrangements were working.
Baroness Scotland said: "How we actively manage violent and sexual offenders to reduce as much as possible the risk they pose is one of the most important questions facing the criminal justice system.
"MAPPA represents a big leap forward in the way we protect our communities from re-offending by violent and sex offenders.
"There has been widespread take-up of the new measures which were introduced in 2004, giving the public protection agencies additional tools to take preventative action against offenders.
"Good examples include the high number of sexual offences prevention orders granted and the number of high risk offenders returned to prison for breach of licence. "
Across the country, there were 28,994 registered sex offenders last year. Registration can last a minimum of two years but many offenders will be on the register for life.