Thirteen men and women suspected of being connected with pay-per-view websites showing images of child sex abuse were arrested in dawn raids.
The arrests followed dawn raids across England
It is the first national operation by the Child Exploitation and Online Protection Centre since it was launched in April.
Three of those held are suspected of being part of an East European gang and of masterminding the sites, CEOP said.
The arrests were in Greater Manchester, London, Wiltshire, Surrey and Kent.
The operation is also the first time arrests have been made in the UK after investigations into pay-per-view internet services.
Jim Warnock, the head of CEOP's dedicated operational response team, said: "We are saying enough is enough and with new legislative powers coupled with specialist, dedicated investigators we can and we will root out those who hide behind complex smokescreens.
"Now we will work to track all the profits made from this illegal service as well as assess the images to make sure all the children involved are now safe from harm."
CEOP also said it is the first tangible result following the set up of its Centre's dedicated financial investigation team.
Mr Warnock added that getting to the heart of any large scale criminal organisation involved complex and painstaking investigation.
"Add to that the international element of this particular swoop and the extra burden of tracing financial online transactions and this was a particularly intricate operation," he said.
The CEOP is affiliated to the Serious Organised Crime Agency (SOCA).