Microsoft Corp lost its appeal against an EU decision penalizing it for defying an antitrust ruling, bringing nearer to an end a decade-long battle with the European Commission over the U.S. software group's business practices.

However, judges at the General Court, Europe's second-highest, reduced the fine by 4.3 percent to 860 million euros ($1.1 billion) from the 899 million euros imposed in 2008. The 2008 fine - about $1.3 billion at the time - amounted to just over 2 percent of Microsoft's revenue for the fiscal year ended June 30, 2008.

The European Commission imposed the penalty four years ago - a record at the time - after Microsoft defied an antitrust decision issued four years previously, by delaying the provision of information to make business easier for its rivals.

The EU regulator said at the time Microsoft had not complied with its order for 488 days.

"The General Court essentially upholds the Commission's decision imposing a periodic penalty payment on Microsoft for failing to allow its competitors access to interoperability information on reasonable terms," the court said in a statement on Wednesday.

But it cut the fine "to take account of the fact that the Commission had permitted Microsoft to apply, until September 17, 2007, restrictions concerning the distribution of 'open source' products".

Microsoft expressed disappointment at the verdict but did not say if it would appeal to the EU Court of Justice, Europe's highest.

"Although the General Court slightly reduced the fine, we are disappointed with the court's ruling," the company said in a statement.

The Commission welcomed the court ruling.

"The judgment confirms that the imposition of such penalty payments remains an important tool at the Commission's disposal," EU Competition Commissioner Joaquin Almunia, who enforces antitrust regulations, said in a statement.

The case highlighted the prickly relations between Microsoft and the European Commission over the last decade.

The company has in recent years taken a more conciliatory approach, marked by a decision to settle another antitrust investigation in 2009 related to the choice of a browser in its Windows operating system.

It has also lodged its own complaints to the Commission about the business activities of rival companies, notably Google Inc.