A judge in the US yesterday threw out a record $1.5 billion (€1.09 billion) award against Microsoft, ruling that the world's largest software company had not infringed on audio technology patents held by Alcatel-Lucent.

Microsoft said the reversal was a victory for other technology companies that could have been at risk to patent infringement charges if Alcatel won.

A federal jury in San Diego ruled in February that Microsoft violated two patents relating to MP3 audio files and handed Alcatel-Lucent the largest ever damages award in a US patent case.

MP3 is the standard digital music format which allows audio to be compressed so it can be played on computers, mobile phones or digital music players.

The court heard a post-trial motion on July 25th and 26th, when Microsoft asked for the verdict to be reversed, a new trial or dramatic reduction in damages.

US district judge Rudi Brewster said that the jury's damages could not stand because Microsoft had not violated one of the two patents.

The judge also called into question the second patent claim in the case, saying Microsoft licensed the technology from German research organisation Fraunhofer Gesellschaft, a co-owner of the patent.

"The court finds the jury's verdict of infringement was against the clear weight of evidence," Mr Brewster wrote in his opinion.

Alcatel-Lucent spokeswoman Mary Ward said the reversal was "shocking and disturbing" and planned to appeal it.

Analysts and lawyers said the ruling had left other providers of hardware and software that support MP3 files, including Apple and Sony, vulnerable to claims from Alcatel-Lucent.