Spanish police say they have arrested 81 persons on suspicion of sexually abusing minors and sharing child pornography on the Internet.

Police say some of the images seized in raids at 80 addresses across the country were "extremely hard" and included some of babies tied up.

A police statement issued by the Interior Ministry said it took a year to track down the participants in the child pornography ring who exchanged videos and photos "that included sadism and bestiality."

Among material seized were 96 hard drives, 58 computers, 68 pen-drives, four tablets, 195 CDs and DVDs, 18 mobile phones and 25 memory cards. The statement addes that one of the addresses raided also contained a marijuana plantation, Saturday's statement says.

It was not immediately clear when the arrests were made.