Amazon.com Inc. (AMZN) denies it violated IBM Corp. (IBM) patents in building its massive retail Web site, and alleges instead that IBM infringed on Amazon's technology to beef up its own offerings.

In countersuits filed Thursday in federal court in Texas, Amazon says IBM's previous legal claims of patent infringement are a meritless and misleading attempt to cash in on its vast patent holdings and Amazon's success.

"IBM's broad allegations of infringement amount to a claim that IBM invented the Internet," Amazon's lawyers wrote in the filings.

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IBM did not return a phone message seeking comment Friday night.

IBM, based in Armonk, N.Y., filed its lawsuits in October in federal court in the Eastern District of Texas. Texas has become a frequent site for patent cases because districts there move quickly and are perceived as relatively responsive to intellectual-property claims.

Amazon, which this year will sell $10 billion worth of everything from books and CDs to pet supplies and jewelry, is accused of infringing on five IBM patents.

IBM says the technologies covered by the patents govern how the site recommends products to customers, serves up advertising and stores data.

In its counterclaims, Amazon denies the allegations and says IBM violated five of Amazon's patents, for ventures including IBM's WebSphere business software.

The countersuits also claim IBM's lawsuits "represent a belated attempt to tap into this dynamic new industry by an old company built on business principles and innovations of the past."

IBM is the world's leading patent holder, spending $6 billion a year in research and development and earning about $1 billion a year in royalties.

Amazon's relationship with patents has been more heavily contested; the company's patent of the "one-click" checkout method in 1999 was derided as overly broad and obvious.

The U.S. Patent and Trademark Office is re-examining that patent.