IBM announced on Monday that it hit Amazon.com with two lawsuits that seek unspecified damages, adding that it attempted to clear up the matter for four years before deciding to sue.

IBM alleges that online retailer knowingly exploits its intellectual property by infringing on several patents that cover, among other things: the presentation of applications in an interactive service; the storage of data in an interactive network; the presentation of advertising in an interactive service; and the ordering of items from an electronic catalogue.

The vendor first notified Amazon.com about the alleged infringement in September 2002, but Amazon.com hasn't wanted to engage in "meaningful discussions," IBM said. Other companies license the patents in question, according to IBM.

Amazon.com declined to comment, saying that it had not yet received official notice of the suit.

The contested patents are at the heart of how Amazon.com operates, an IBM spokesman said. IBM doesn't resort to lawsuits very often, so the decision to take this step reflects how seriously IBM takes this matter, he said.

"Rather than build its business on its own technologies, Amazon has relied on IBM's innovations, unlawfully taking and using them for its business," IBM wrote in one of the complaints.

IBM is entitled to royalties on the billions of dollars in revenue that Amazon.com has generated through its "unlawful infringement" of the patents, one of the complaints states. The company also seeks injunctive relief to prevent Amazon.com from continuing the alleged infringement. The lawsuits were filed separately in two district courts for the Eastern District of Texas, US.