Metropolitan Police lose track of 123 sex offenders
The whereabouts of 123 registered sex offenders are unknown to the Metropolitan Police (Met).
Some of them have been missing for as many as 14 years. The Met believes 48 have been living outside the UK.
Police said they lost track of offenders after they failed to notify the police of their change of address.
The number is only just up from the 121 reported missing last May but sex abuse victims' groups said every offender "going off the radar is a concern".
Donald Findlater, from the Lucy Faithfull Foundation, a UK-wide charity dedicated to reducing the risk of children being sexually abused, said: "It's important that if within this 123 there are any sex offenders who pose a likely immediate risk to children, that information needs to be put across to the public.
"If the police don't know where they are then it is vitally important that police share that information with other agencies and the public."
He added: "Many of them fail to keep police informed because they just don't want to be monitored, not because they're dangerous.
"The biggest risk to children across the country isn't posed by registered sex offenders, it's posed by people not on it at all."
He said police and other agencies are responsible for monitoring more than 4,000 convicted sex offenders in the capital.
A spokesman for the Met said: "We take this matter extremely seriously and officers are proactively following lines of inquiry in order to trace these offenders to ensure that they are dealt with robustly for having breached the terms of their conditions."