Swiss police say they have uncovered an internet child pornography network spanning 78 countries and involving at least 2,000 IP internet addresses.
An inquiry was launched after a tip-off from Interpol about a website based in Switzerland being used as a forum for illegal child pornography films.
The site was officially devoted to hip hop music but was used to access videos of child pornography via secret codes.
The site designer was unaware of how it was being used, Swiss media report.
Swiss federal police spokeswoman Eva Zwahlen said the authorities had been monitoring the website in the south-western canton of Vaud, the Associated Press reports.
She confirmed a Swiss newspaper report that the investigation involved people from the US, Poland, Greece and other countries.
Jean-Christophe Sauterel, a police spokesman in Vaud, told Swiss newspaper Le Matin Dimanche that it was "the biggest concern of its kind dismantled in Switzerland".
According to the newspaper, dozens of arrests and several convictions have been made as a result of the investigation, which began in May 2008.
Speaking about suspected users of the illegal material in Switzerland, Mr Sauterel said none of them were based in Vaud itself.
The website's owner told the newspaper of their shock at being told by police about how it had been used illegally.
The site's designer was not aware what it was being used for and was cleared of any involvement in the ring, police were quoted as saying by AFP news agency.