BRUSSELS, Belgium – The European Union threatened yesterday to fine Microsoft up to $2.37 million a day for failing to obey its 2004 antitrust ruling, accusing the company of intransigence in sharing information with competitors.

“I have given Microsoft every opportunity to comply with its obligations. However, I have been left with no alternative other than to proceed via the formal route to ensure Microsoft’s compliance,” the E.U. antitrust commissioner Neelie Kroes said.

The threat of new sanctions against Microsoft aims to force it to provide more detailed information so competitors’ products can be made more compatible with Microsoft’s Windows server operating system.

It follows an independent computer scientist’s scathing assessment of what Microsoft has thus far provided, and set off a new round of bickering between the software company and regulators.

Microsoft’s top lawyer, Brad Smith, accused the E.U. Commission of threatening the fine before it had even reviewed highly technical documentation he said Microsoft sent to European officials on Wednesday.

“We don’t understand how they can reach these conclusions because they haven’t read or reviewed these documents,” Mr. Smith said.

He also expressed frustration with the European Union’s repeated requests for information.

“Every time we do absolutely everything we’ve been asked to do, we’re told that there’s something else we need to do,” Mr. Smith said in an interview with the Associated Press.

An E.U. spokesman, Jonathan Todd, said the E.U. had not yet received copies of the documents that Microsoft said it sent. The European Commission takes its Christmas vacation today so the delay, in effect, forces the E.U. to wait until the second week of January before it can assess any changes.