Sites including the Pirate Bay are worst-affected by Google's Pirate update. Wikipedia Commons Google has pushed out an update to its search algorithm that is making it even harder for people to discover free movie and music torrents, with sites like Pirate Bay, Isohunt and Torrentz.eu among the worst affected by the rollout.

The rollout comes a month after Robert Thomson the chief executive of News Corp — which owns The Times and New York Post titles — attacked Google, calling it "a platform for piracy," in a letter to the European Commission.

Earlier this month Google published a refresh of its "How Google Fights Piracy" report, detailing its efforts to combat piracy across its platform.

Google's “Pirate” update was first introduced in August 2012. It was designed to prevent sites with copyright infringement complaints, filed via Google’s DMCA system, from ranking highly in Google’s search listings. It acts as a filter, applying a downgrade to sites that have received DMCA complaints.

The latest update to Google’s anti-piracy measure is more far-reaching than before. Some sites have seen up to a 98% markdown in visibility on Google's search listings, according to early analysis by Searchmetrics.

Pirate affects sites the most that carry search keywords such as “download free movies,” “watch [movie name] online free,” online free movies,” “movies download,” “watch [movie name]” and “where can I watch [movie name] online,” Searchmetrics’ founder Marcus Tober details in a blog post.

Some of the worst affected by the downgrade include popular torrent sites such as Kickass.to, Thepiratebay.se, Torrentz.eu and Isohunt.

The charts below show how the SEO visibility for sites include movie4k.to, free-tv-video-online.me and downloads.nl fell off a cliff as soon as the latest update was implemented.

Download.nl

Free-tv-video-online.me Searchmetrics

Movie4k.to

And here’s the full “top 30 loser list,” according to Searchmetrics