Police forces in Yorkshire have lost track of 20 registered sex offenders, according to a report published by Sky News.
West Yorkshire Police currently have 10 offenders who are wanted for breaching of registration requirements, while South Yorkshire Police said 10 registered sex offenders were wanted because their whereabouts were unknown.
Nationally, 485 sex offenders have been lost track of, including rapists and paedophiles.
Three of the 10 that West Yorkshire Police are looking for are known to be living outside the UK and four offenders have been wanted for more than a year.
Out of the 10 that South Yorkshire Police are tracking, offences include assault on a female by penetration, indecent assault on a female under 14, making indecent photos of children, rape, sexual assault, sexual activity with a female under 16, sexual activity with a child and taking indecent photos of children.
North Yorkshire Police said no registered sex offenders were currently missing.
Michelle Skeer, National Police Chiefs' Council lead for the Management of Sexual Offenders and Violent Offenders, said: "The number of recorded wanted or missing sex offenders represents less than 1 per cent of the total and a proportion of these are, following investigation, either known or believed to be living abroad or have returned to their country of origin.
"When registered sex offenders are missing or wanted in the UK, all police forces are alerted. If they return to the UK, there are processes in place to ensure that they are brought to the attention of police and arrested where appropriate.
"The UK has some of the most effective tools in the world to manage registered sex offenders.
"While the reality is that the risks posed to the public by such individuals can never be completely eliminated, there is significant evidence that the multi-agency public protection arrangements successfully keeps them to a minimum."
Forces across the UK were asked to reveal the number of registered sex offenders whose whereabouts were unknown on 17 January.
41 forces responded to Sky News' request, while four did not.