Known sex offenders and violent criminals living in the community are not being monitored regularly, a Home Office report has said.

The new study found a "severe shortage" of approved accommodation for offenders as well as insufficient treatment programmes or lengthy waiting times as well as a lack of funding as cases continue to increase.

In 2005-06, there were 29,973 people on the sex offenders register, an increase of 4 per cent on the previous year. According to figures published under the Freedom of Information Act, police have lost track of 322 of these.

The number of violent offenders who need regular supervision was put at 14,317, a rise of 13 per cent on the same period one year before, while 3,363 needed supervision following sentencing or after they left prison.

However, supervision visits to offenders deemed to be medium or low risk occurred annually rather than the recommended three to six-month interval, it found.

Multi-Agency Public Protection Arrangements (Mappa) - tasked with monitoring offenders and preventing reoffending - were introduced in 2001, bringing together the police, probation and prison services.

The study, written by experts from De Montfort University, Leicester, praised Mappa but said: "A key concern was how to respond to the inevitable growth in the number of offenders subject to registration, and there were grave concerns that resources were not increasing as the registration list does."

"Participants expressed concern about increases in workload which they felt would be an inevitable consequence of any public disclosure requirements.

"Of particular concern was the potential impact on police resources and the diversion that issues such as offender 'outing' and subsequent rapid relocation of offenders to places of safety, and other related public disorder might mean for the supervision of cases."