An international police sting operation has been launched to catch paedophiles who go online for images of children.
Details of internet users visiting the sites could be sent to 180 countries
Forces in countries including Britain, Canada and Australia have set up sites appearing to offer child pornography.
But instead of finding the images they want, users are told they could face 10 years in jail and may have their details circulated to 180 countries.
Jim Gamble, Assistant Chief Constable of the National Crime Squad, wants to hit paedophiles' confidence on the net.
Operation Pin, which was developed by a specialist unit in the West Midlands, is the first such attempt to warn offenders that police know they are committing a crime.
Visitors to the sites, which appear to be identical to real paedophile addresses, go through a series of web pages searching for exactly the image they want.
When they try to view the picture they will be told they have committed a crime for which they could spend 10 years in jail and that their details have been recorded.
Mr Gamble said: "If you are a paedophile and you are out there, we are going to make it much more difficult for you to operate.
"You won't have the confidence to be sure that when you press enter the site you are entering is not a law enforcement site."
The website was devised following Operation Ore, which gave UK police the details of 7,200 internet sex and has so far led to more than 3,000 computer searches.
More than 723 people were charged as a result and 277 have already been convicted.
Mr Gamble said: "It has given us a bit of a wake-up call - we have learnt from Operation Ore."
He said that people who view images of children create a demand for new images and further sexual abuse, which takes place every day.
Hard drive amnesty
Welcoming the initiative, Dr Ute Nevidi from Childline, told BBC News: "This new operation should actually serve to deter a number of people actually going online and looking for images of child sexual abuse.
"Every year Childline hears from well over 8,000 children who are facing sexual abuse."
Operation Pin comes just over a week after police said they were considering launching a computer hard drive amnesty as part of a targeting of internet sex offenders.
The scheme, which would operate in a similar way to a gun amnesty, would aim to prevent child abuse by getting people who have images of children to volunteer for counselling.