Nineteen arrests were made in Spain, with the remainder in France, Italy, Sweden, the Netherlands, Argentina, Chile, Costa Rica, Mexico, the Dominican Republic, Panama and Uruguay, said Spanish police who coordinated the operation.

“We are going to continue to carry out this kind of operation against child pornography in determined fashion as it is a disgrace which democratic, free and decent societies cannot tolerate,” Spanish Interior Minister Jose Antonio Alonso said.

The police investigation began in the north-western city of Pontevedra in January and turned up more than 20,000 items of child pornography, including videos, photographs and MP3 files accessed via a Spanish-language Internet chat room.

Police began monitoring visitors to the chat room and within a fortnight had tracked some 900 connections to the website from around the globe.

Spain then liaised with police forces of the countries concerned before staging raids on homes, in which video cameras and documents were also seized.

“Several meetings were organised during the operation involving magistrates from all the countries concerned,” a Spanish police statement said.

The Spanish arrests were nationwide, with several made in Madrid and other major cities including Barcelona and Valencia.

Few details were immediately available as to how many people had been detained in the other countries whose nationals were involved.

Swedish police spokesman Linda Widmark said that no one in Sweden had been arrested although Swedish criminal police participated in planning the raids.

The Dutch news agency ANP said the operation was not believed to have involved many Dutch nationals.

According to Spanish police the operation was not directly linked to previous swoops on paedophile rings in the country.