Six men were arrested on 11 November, including several employed in IT management or consultancy. The men are believed to be part of a software piracy group called Drink or Die (DOD).
Search warrants were executed on 11 addresses in Staffordshire, Kent, London and Merseyside, where hardware and software was seized.
DOD is allegedly responsible for pirating millions of pounds-worth of software, games, music and digital videos through Internet sites across the globe.
The NHTCU said: "DOD is one of the largest international and most sophisticated 'warez' [pirated software] organisations."
These groups crack software, remove serial numbers, tags and other forms of protection, and post it on the Internet for illegal distribution by other members of the group.
Detective Superintendent Mick Deats, deputy head of the NHTCU, said: "[We are] sending out a powerful message to people who may wish to commit these types of crime, that policing is matching them every step of the way."
Other arrests have been made in the US, Australia, Finland and Norway.