Tracking internet paedophiles
6 September 2013 Last updated at 19:13 BST
Police say more must be done to recognise the link between the viewing of child pornography and sexual abuse.
David Cameron has put pressure on internet providers and search engines to prevent paedophiles from viewing indecent images.
But Lancashire Police, which has seen a rise in such activity in the last three years, says the police also have a responsibility to uncover illegal activity online.
Chris Buckler reports.