Four major record labels have field a copyright infringement lawsuit against the defunct file-sharing site Megaupload and its founder Kim Dotcom.

The lawsuit was filed on behalf of Warner Music, UMG, Sony and Capitol and comes three days after Motion Picture Association of America (MPAA) filed a similar complaint.

They claim Megaupload has earned more than $175m from pirated content and are causing "more than half a billion dollars in harm" to copyright owners.

Criticising both the lawsuits Dotcom’s US attorney Ira Rothken was cited by Ars Technica as saying that the RIAA, MPAA and DOJ are like three blind mice following each other in the pursuit of meritless copyright claims.

"We believe that the claims against Megaupload are really an assault by Hollywood on cloud storage in general as Megaupload used copyright neutral technology and whatever allegations they can make against Megaupload they can make against YouTube, Dropbox, and others," Rothken said.

The latest suits come as Dotcom fights a bid by US authorities to push him out of New Zealand to face online piracy charges over thewebsite.