An investigation into a Europe-wide child pornography network has led to 92 arrests across eight countries, prosecutors say.
Some of the pornographic material was sold online
The network made videos of children being abused and sold them to 2,500 customers in 19 countries, says the European police force, Europol.
The films were mainly produced in Ukraine, Belgium and the Netherlands, and most of the victims were Ukrainian.
More than 40 of the arrests were made in Britain, European prosecutors say.
Police have seized thousands of computers, videos and photographs in their investigation - code named Operation Koala.
The investigation began in July 2006, when police in Australia found a video on the internet showing an adult abusing two young girls.
The girls were identified by police in Belgium and the offender, their father, was arrested.
He in turn led investigators to the producer of the video, an Italian man who operated in Belgium and the Netherlands but also owned a studio in Ukraine.
The names of 2,500 customers were recovered from his computer.
An analyst for Europol, Menno Hagemeijer, said the customers came from many different countries and all walks of life.
"We have identified schoolteachers, swimming instructors, lawyers, IT specialists," he said.
Mr Hagemeijer said the videos had been "tailor made", with customers ordering specific acts to be performed by specific children.
Twenty-three children aged between nine and 16 who were shown being abused have been identified. Twenty-one are from Ukraine and two from Belgium.
European prosecutors have stressed that the operation is continuing and there are likely to be further arrests.