Nearly 4,000 websites linked to pirated content are now being blocked by the UK's major ISPs.
Data provided to TorrentFreak by a leading broadband supplier shows it now prevents customers from accessing 3,814 URLs as it looks to limited the illegal availability of copyrighted material through its network.
Many of these sites are proxies, which redirect to known providers of illegal content, such as The Pirate Bay.
Under UK law, copyright holders do not have to file a new case if they want to expand blocklists every time a new proxy becomes available. This means the list of blocked domains has grown rapidly in recent years.
ISPs are investing substantial sums of money in maintaining these blocks in order to satisfy rights-holders. According to ISPreview, Virgin Media spends a "low five-figure sum" annually on introducing blocks and maintaining the list of blocked URLs to prevent customers from accessing material illegally.