There are 690 dangerous sex offenders living in Northern Ireland, according to latest figures.
The statistics, released in a new report by the Northern Ireland Sex Offender Strategic Management Committee on how to best manage the risk, show the number of rapists, paedophiles and sex attackers is up 15 per cent since last year.
Up to ten of them are being hunted by police at any one time for failing to notify the authorities of their new living arrangements.
One of the highest concentrations appears to be in north and south Belfast, according to William McAuley, strategy and policy co-ordinator of the committee.
He said the organisation had set out three figures, the first showing that 9,036 convicted sex offenders are now living in Northern Ireland. Out of those, 690 are being scrutinised through risk assessment and risk management.
"There is an identifiable increase of 15.3 per cent in the last 12 months of sex offenders being managed under our arrangements," Mr McAuley said.
Every time somebody new is convicted, their name is added to the criminal database.
Amid fears that some of the most dangerous offenders could go underground, Mr McAuley stressed that few go missing.
"There's a number of people subject to notification requirements who have failed to notify police of a change of address. These people are being pursued by police, but there's only a tiny number," he said.
Additional reporting: PA