Spotify said on Monday it had shut down accounts linked to a piracy activist group that claimed it copied millions of the platform’s music files and metadata.

The group Anna's Archives said in a blog post it had backed up 86 million Spotify tracks and the metadata for 256 million tracks, a process known as "scraping", in order to start an open "preservation archive" for music.

Anna's Archives said the 86 million music files represented more than 99.6% of Spotify "listens", while the metadata copies represented 99.9% of all tracks on Spotify.

The breach, which has no impact on Spotify users, means that in theory anyone could use the information to build their own free music archive, though in practice they would be swiftly pursued by rights holders.

"Spotify has identified and disabled the nefarious user accounts that engaged in unlawful scraping," the company said in a statement sent to AFP.

"We've implemented new safeguards for these types of anti-copyright attacks and are actively monitoring for suspicious behavior," it said.

"Since day one, we have stood with the artist community against piracy, and we are actively working with our industry partners to protect creators and defend their rights."