Authorities in western Germany are investigating 30,000 people suspected of taking part in a child abuse network.
Peter Biesenbach, Justice Minister for the North Rhine-Westphalia state, told reporters on Monday that the investigation's findings so far were "extremely disturbing".
"We need to recognise that child abuse is more widespread online than we previously thought", he added.
The probe was launched in October after police arrested a man in Bergisch Gladbach, near the city of Cologne.
Investigators who searched his premises found vast amounts of electronic evidence that revealed the existence of a large paedophile network.
Biesenbach said that "more than 30,000 unknown potential suspects" were being probed as part of that single investigation.
"The challenges that such crimes pose to the judiciary are enormous," he explained.
"The acts are not only committed by individual offenders but in an online network of sympathizers, supporters, assistants and accomplices.
"They exchange information, pictures and videos of their deeds and use the technical possibilities of the internet to communicate undetected with each other under pseudonyms in chat groups," he went on.
Seventy-two suspects across Germany have so far been identified while 10 people have been arrested and a further eight have been indicted.
Officials say 44 victims have been identified, including a three-month old baby.
A nationwide special task force to identify the tens of thousands of suspects has been set up.