Some of the biggest record labels in the world have sued a popular website that converts YouTube videos into .mp3 audio files. The group says that YouTube-mp3.org facilitates copyright infringement through its stream-ripping service.

The BBC reports that Universal, Warner Bros, Sony Music, and others have launched a lawsuit against the German operator of the site in Los Angeles federal court. They are seeking damages that include $150,000 for every alleged instance of piracy.

The site works by simply inputting a YouTube URL, hitting the convert button, then downloading the audio track taken from the video. The Recording Industry Association of America said that YouTube-mp3.org's 60 million users per month made it the largest website of its kind, responsible "for upwards of 40 percent of all unlawful stream-ripping of music from YouTube in the world."

The labels say that "tens, or even hundreds, of millions of tracks are illegally copied and distributed by stream-ripping services each month" and that YouTube-mp3.org is the "chief offender."

"This site is raking in millions on the backs of artists, songwriters and labels," said Cary Sherman, Chairman of the Recording Industry Association of America, in a statement.

"We are doing our part, but everyone in the music ecosystem who says they believe that artists should be compensated for their work has a role to play. It should not be so easy to engage in this activity in the first place, and no stream ripping site should appear at the top of any search result or app chart."

The claim includes 304 songs that the labels allege have been illegally stream-ripped through YouTube-mp3.org, including tracks from Meghan Trainor, Sia, Missy Elliott, Sugar Ray, James Blunt, and One Direction.

YouTube-mp3.org has not commented on the case. The website claims that it copies music to its own servers. "Different from other services the whole conversion process will be performed by our infrastructure, and you only have to download the audio file from our servers."

The music industry also took aim at those organizations it believes support stream-ripping sites. "We hope that responsible advertisers, search engines and hosting providers will also reflect on the ethics of supporting sites that enrich themselves by defrauding creators," said BPI Chief Executive, Geoff Taylor.

A hearing date has yet to be set.