– Jon Brown, head of the NSPCC's sexual abuse programme
It's a very worrying situation and more research is needed on the most effective punishment and treatment of offenders caught viewing child abuse pictures.
"Trying to stop the terrible trade in these images is obviously a huge task.
"But it mustn't be seen in isolation. It's part of a much bigger sexual abuse problem."
Some 76 people have been arrested during 48 hours of raids as part of an operation targeting suspected internet paedophiles. Earlier, the Child Exploitation and Online Protection (Ceop) warned that abusive images are becoming more extreme.