Some paedophiles with images of child abuse will escape prosecution, the head of the National Crime Agency says.
Keith Bristow said expecting all the estimated 50,000 people in the UK who have accessed abuse images to be brought to justice was “not realistic”.
He said police would have to focus on those who posed most risk.
Labour called it “disgraceful”, adding that the NCA was not fit for dealing with the problem. The Home Office said all crimes should be investigated.
Some 660 arrests were made during a recent operation targeting people who had accessed child abuse images online.
However, the BBC understands that as part of that investigation, as many as 20,000-30,000 individuals were identified as potential offenders.
The Child Exploitation and Online Protection Centre (Ceop) – part of the NCA – has estimated that 50,000 people in the UK are involved in downloading and sharing images of child abuse.