Microsoft has been handed a whopping great bill by an American judge after he upheld a previous court patent case ruling against the computing giant.

At the end of May, Microsoft lost a patent case against telecoms company Alcatel-Lucent.

The computing giant had accused Alcatel-Lucent of infringing patents business telephone network technologies.

In particular, it pointed to four patents for the software in a system that integrates telephones with computers for calls, messages and videoconferences.

But the court threw out the case and now US District Judge Marilyn Huff has determined that Microsoft owes Alcatel-Lucent a total of $512 million, which includes interest on the original award.

"We had always believed we had a strong case and are pleased that the judge agreed that the jury's thoughtful verdict was well reasoned and supported by the evidence", Alcatel-Lucent spokeswoman Mary Ward said in a statement.

A Microsoft spokesman said the company said it plans to appeal the decision and is confident that the damages award will not be sustained on appeal.