British police have arrested 660 suspected paedophiles - including doctors, teachers and care workers - in a six-month operation targeting people watching indecent images online, the National Crime Agency said yesterday.
The massive investigation identified 431 children who were in the "care, custody or control" of the suspects, including 127 who were deemed to be at immediate risk of harm.
They have now been made safe, the NCA said, without giving further details.
All the suspects were arrested for downloading or distributing child abuse images, but charges brought so far include serious sexual assault.
Britain has been rocked by a series of paedophile scandals in the past two years, since revelations that late BBC television host Jimmy Savile was a serial sex offender. The government recently launched an inquiry into the institutional abuse of children following allegations of a sex abuse ring involving senior politicians in the 1980s.
The NCA stressed that none of those arrested in the operation is a serving or former lawmaker or member of the government.
About 45 police forces across England, Scotland, Wales and Northern Ireland took part in the "unprecedented" operation involving searches of 833 properties and more than 9,000 computers, phones and hard drives.
"This is the first time the UK has had the capability to coordinate a single targeted operation of this nature," said NCA deputy director general Phil Gormley.
He added: "I am pretty appalled about what it says about human nature."
Some of those arrested in the NCA operation had unsupervised access to children in the course of their work, including scout leaders and former police officers. Only 39 of those detained had previously come to the attention of police.
Child protection campaigners praised the operation, but said police would need more help from the communications industry in the future.
Claire Lilley, head of online safety for the NSPCC children's charity, called on the industry to find "inventive ways of blocking the flow of such horrendous pictures".