Some 200 people are being investigated over an internet pornography site showing young children being tortured, Italian police say.
Suspected members of the paedophile ring are said to include three priests and a mayor, media reports say.
The children were aged between four and eight. No arrests have yet been made.
Child protection organisation head Antonio Marziale said the case was just the tip of the iceberg.
He told the Italian news agency Ansa that fighting paedophilia should be at the top of the government's agenda.
"The children on the films were aged between four and eight at most. Some were abused, others were even tortured," said Domenico Di Somma, co-ordinator for the police computer investigation taskforce.
The anonymous website was password-protected, but a tip-off to a child abuse telephone helpline allowed computer experts to track down the users, Reuters news agency reports.
The investigation is said to centre on the island of Sicily.