Microsoft scored a victory in its anti-trust wrangles with Google yesterday as a US federal court judge rejected the search company's attempt to force an extension of government oversight of Microsoft's activities.

Judge Colleen Kollar-Kotelly, who oversees the terms of the four-year-old agreement that settled the US anti-trust case against Microsoft, refused to consider Google's application to have the agreement extended beyond November, when large parts of it expire. She added that Google's only course of action was to lodge its complaint with the US department of justice - a body that has already said it is satisfied that no further action is needed.

According to some legal experts, Google's attempt to intervene in the regulatory oversight of Microsoft marked a new and unwelcome step in the battle between the two rivals.

Google's move was the latest example of how big companies have tried to use the anti-trust process to prevent competition, said Ron Cass, chairman of the Center for the Rule of Law.