Media company Discovery Communications Inc has sued, 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.

Amazon launched the second version of its digital e-reader last month. The wireless device, which retails for $359, has been closely watched by gadget lovers and touted by Amazon as the future of book reading. It first came to the market in November 2007.

An Amazon spokeswoman declined to comment on the lawsuit.

Discovery, which is not a competitor to Amazon and is best known for its Discovery channel on U.S. cable television, is seeking damages and a royalty to compensate it for any future infringement of the patent.

Discovery and founder Hendricks were significant players in the development of digital content and delivery services in the 1990s, the company said in a statement. Hendricks' work included inventions of a secure, encrypted system for the selection, transmission and sale of electronic books.

Sony Corp also sells a portable reader, but a Discovery spokeswoman declined to comment on whether the Japanese company's technology could also be in violation of the patent in question.

Amazon's new Kindle has been dogged by criticism from the publishing industry, which says a text-to-speech function that allows users to listen to their devices avoids paying royalties to authors.

The Author's Guild has called the speech function a significant challenge to the publishing industry, but has not filed a lawsuit.

Mollifying critics, Amazon in February said it would allow the audio function on the new Kindle to be disabled, but asserted the feature was legal.

(Editing by Lisa Von Ahn)