IBM has sued Amazon.com for alleged patent infringement.

It is claimed that Amazon.com has violated at least five IBM patents relating to ecommerce.

"We filed this case for a very simple reason. IBM's property is being knowingly and unfairly exploited," said IBM's senior vice president of technology and intellectual property Dr John E Kelly III.

Several of the patents cited as being violated by IBM date back to the infancy of ecommerce in the early 1990s. Filed between 1990 and 1995, the patents include such concepts as storing and presenting data in interactive applications (such as a web browser); the presentation of advertising in interactive applications, and the system of ordering items from an electronic catalogue.

The suits were filed in the Lufkin and Tyler division courts in the eastern district of Texas.

Other companies have licensed the patents from IBM both individually and by taking out 'field of use' patent licences, according to the company.

IBM claims to have first notified Amazon.com of the infringements in 2002, but said that Amazon showed "no willingness to have meaningful discussions".

Amazon declined to comment on the case.

This is not the first time Amazon.com has been accused of patent infringement. In 2004, the company paid Soverain Software $40m to settle an ecommerce patent lawsuit.