More than 500 people are being targeted in an international operation to fight child pornography, Spanish police say.
Spain's interior minister says more people could be detained
Police in 12 countries from Uruguay to Switzerland are participating in the raids, aimed at child pornography on the internet, the Civil Guard say.
Reports say more than 20,000 items - including videos, photos and MP3 audio files - were involved.
Spanish Interior Minister Jose Antonio Alonso says more arrests could be made, the BBC's Danny Wood in Madrid reports.
The operation follows a two-month investigation that uncovered some 900 locations where indecent material was stored on the internet.
It was prompted by a complaint to the police from a Spaniard who told the authorities he had seen graphic child pornography in an internet chatroom.
Police monitored the site and listed more than 900 internet addresses logging on to the site over a period of two weeks.
The Spanish news agency Efe reports that police seized video cameras, CDs, videos and photos as part of the raids.
The agency reported that the images included "highly aggressive" depictions of very young children.
Arrests were made in eight regions across Spain, and Spanish police said more were expected in France, Italy, Sweden, the Netherlands and seven Latin American countries, including Mexico, Chile and Argentina.
The arrests are apparently not connected to earlier Spanish operations against paedophiles.
Spanish police arrested nine people in January in connection with child pornography, and 90 people were arrested in November in raids in which thousands of photos and DVDs depicting child abuse were also seized.