A 20-year-old man in Nottingham has been arrested on suspicion of running a proxy server providing access to websites blocked in the UK.
He was released on bail following questioning by the City of London's police intellectual property crime unit (PIPCU) as part of Operation Creative, an anti-piracy campaign.
Detective chief inspector Andy Fyfe, head of PIPCU, said: "This week's operation highlights how PIPCU, working in partnership with the creative and advertising industries, is targeting every aspect of how copyrighting material is illegally being made available to internet users.
"We will come down hard on people believed to be committing or deliberately facilitating such offences."
The proxy server in question is thought to have linked to 36 other websites blocked for hosting "illegal or infringing content".
As part of Operation Creative police are replacing advertisements on copyright infringing webpages with warnings to visitors that the sites are under investigation.
Proxy servers have been one of several ways that users have sought to circumvent site blocking orders, according to Kieron Sharp, director general of the Federation Against Copyright Theft (FACT).
"This operation is a major step in tackling those providing such services. FACT will continue to support PIPCU in their enforcement activities," he added.