The music giant had made a deal with San Diego-based AnywhereCD that allowed CD buyers to rip their albums into MP3 files.
But Warner has now accused AnywhereCD of selling its music in a manner that "flagrantly violates" the agreement. The site was launched last week by MP3.com founder Michael Robertson.
Warner said in a statement: "We have sent them a notice of termination. They are required to immediately remove all of our content from their site."
The news comes a week after Warner rival EMI unveiled a more relaxed approach to copyright management, allowing retailers such as iTunes to sell its music without DRM.
Warner shows little sign of following suit. In February the company's chief exec Edgar Bronfman told investors that selling digital music without protection was not fair or logical.
"There is no reason that music is the one content category that should not or cannot be protected," he said.
Warner accuses website of DRM violation
By Jane Hoskyn on Apr 17, 2007 2:31PM
Warner Music Group has demanded that its music be removed from a new online retailer, after the site sold digital downloads without copy protection software.
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