The Justice Department and 19 states in the Microsoft antitrust case yesterday urged an appeals court to uphold findings that the company broke the law and should be split in two to prevent future violations.

In a filing with the US Court of Appeals, the government said the Microsoft matter was "a classic case of monopolisation" in which market dominance was used to sustain or extend that power.

Microsoft told the appeals court in November that the trial court proceeding was "infected with error" and the break-up order was "extreme".