Illegal music downloads are booming despite the FBI's ongoing anti-piracy campaign and the existence of legitimate sources like iTunes and Spotify, according to new research.

Musicmetric revealed that Torrent downloads had surpassed the three billion milestone during the first half of 2012 on Monday.

Within the UK the agency reported detecting 43 million album and single release downloads during the period.

The figure makes the UK the second biggest Torrent downloader, only beaten by the US, where Musicmetric reported detecting 96 million downloads.

Musicmetric's findings come after numerous measures by law enforcement to stop online piracy, including blocking several file sharing sites like the Pirate Bay.

"For the first time, we have evidence that blocking Pirate Bay had little effect on BitTorrent downloading," said Gregory Mead, chief executive of Musicmetric.

"The challenge for copyright holders is to find ways to monetise music files 'torrented' online. While the file sharing network is largely ignored as a proactive channel, little progress can be made on figuring out how this might be possible."