A US appeals court has upheld a ruling that Microsoft's Office software infringes on a Guatemalan inventor's technology, lawyers for the inventor said Friday in the US.

Law firm Morrison & Foerster said that on Wednesday in the US, the United States Court of Appeals for the Federal Circuit in Washington affirmed a verdict that Microsoft's Office software infringed on a patent held by Carlos Armando Amado. In June 2005, an Orange County, California, jury awarded Amado US$6.1 million, ruling that Microsoft's method of linking its Access database and Excel spreadsheet infringed on Amado's technology.

"This ruling signals the validity of the patent and confirms Microsoft's liability of infringement on Mr. Amado's software program," Vince Belusko, a Morrison & Foerster partner, said in a statement. A Microsoft representative did not immediately have a comment.

Both sides had appealed the original verdict, with the court rejecting both appeals. The appeals court said it would let the lower court decide how much, if any, of escrow funds should go to Amado.

"When the district court makes that determination, any party believing itself aggrieved by that order may appeal to this court," the court said in its ruling.

Morrison & Foerster said it is hoping that the federal court will award Amado further damages for continuing infringement, out of an escrow account that now has more than US$65 million in it.

"We are hopeful that the District Court will now award Mr. Amado substantial monies from that escrow account when the matter is returned to the court."

Since the jury verdict last year, Microsoft has altered Office, alerting businesses back in January that they will need to upgrade to the modified version.