Microsoft has been ordered to pay $388 million (£246 million) after losing a six-year legal battle with an Australian inventor over intellectual property.

A US court ruled that the computing giant wilfully infringed a patent owned by Uniloc, a developer of anti-piracy software, when it launched programs using similar software for its Office and Windows XP products about a decade ago.

The damages payout is one of the largest ever infringement awards.

Ric Richardson, the founder of Uniloc, showed his software to Microsoft bosses in 1993. In a David and Goliath-type fight, he took on the company in 2003, arguing that it had pocketed billions of dollars from infringing his patent.

Microsoft said that it had developed its own software, and is asking the court to overturn the verdict.

Spokesman David Bowermaster said: “We are very disappointed in the jury verdict. We believe that we did not infringe, that the patent is invalid and this award of damages is legally and factually unsupported.”