Dutch researchers say 1,000 men from around the world made contact with a 10-year-old 'girl' in the Philippines during a 10-week investigation, many of whom wanted to pay her to take off her clothes in front of a webcam.
Children's rights organisation Terre des Hommes set up the fake profile of a girl named Sweetie in an online chat room and its specially trained researchers were astounded by the avalanche of responses.
One researcher described it as 'petrifying' but said the real worry now was the number of girls from developing nations getting access to the internet and parents and criminals trying to make money out of them.
The information gathered during the investigation will be passed to Interpol.
The BBC's Angus Crawford was invited to a secret location to see how the work is carried out.