Media company Discovery Communications Inc has sued Amazon.com, accusing the online retailer’s Kindle of infringing its patent on electronic book technology.

The lawsuit, filed on Tuesday in U.S. District Court in Delaware, marks another blow for a closely watched gadget that has drawn fire from publishers that say Amazon is trying to avoid paying royalties.

The lawsuit claims that Amazon, in two versions of its Kindle, has infringed one or more of the claims on a patent that Discovery founder John Hendricks received in November 2007.

The patent deals with encryption technology for the distribution of digital books.