The Court of First Instance, the EU's second-highest court, decided against granting Microsoft a suspension on an EU antitrust order issued against the software company earlier this year.

In March, after a five-year investigation, the EU Commission slapped a record fine of €497 million ($665 million) on Microsoft after finding that the company had abused its leading market position in the computer operating systems market to hurt competitors.

Brussels also ruled that the company had to offer a European version of its Windows operating system stripped of its own multimedia software, and provide competitors with the source information they need to enable their products to better integrate with Windows.

Microsoft had appealed to the court, first to cancel the antitrust decision. The court is not expected to rule on this for several years. The second appeal -- the subject of Wednesday's verdict -- sought suspension of the measures imposed by the Commission until the first appeal had been completed.

Data protection main concern

Microsoft has already paid the EU-imposed fine, but the company has fiercely opposed any measures that could affect its core strategy, which is based on the integration of new features into the Windows operating system.

The company argued it would suffer "irreparable damage" if it were forced to pass on confidential programming information to competitors in compliance with the EU order.

But Microsoft failed to convince the court that it had a reasonable case, that it urgently needed relief, and that the balance of interests between it and the public weighed in its favor.

"Microsoft has not demonstrated specifically that it might suffer serious and irreparable damage," the court said in a document obtained by Reuters.

The president of the court, Bo Vesterdorf, said that "a number of questions of principle were raised" but that "the requirement relating to urgency is not satisfied."

The EU Commission argued that the sanctions would be rendered meaningless if delayed, because the market would have moved on by the time they were implemented.

Either side can appeal Wednesday's decision to the EU's highest court, the European Court of Justice.