The European Commission handed down a combined fine of 1.35 billion euros to Pilkington, French group Saint Gobain and two other companies in 2008 for price-fixing in the car glass market over a five-year period starting from 1998.

Pilkington subsequently challenged the decision at a lower court, lost and then appealed to the Luxembourg-based Court of Justice of the European Union (ECJ).

The ECJ upheld the EC ruling, rejecting Pilkington's argument that its fine was proportionally higher than the other because it is a less diversified company.

"The Court of Justice finds that it is not contrary to the principles of proportionality and equal treatment that an undertaking ... may receive a fine which represents a proportion of its overall turnover that is greater than that imposed on the other undertakings," judges said.

The fine is the third biggest sanction levied by the Commission.

(Reporting by Foo Yun Chee; Editing by Greg Mahlich)