The European Commission raised doubts Thursday that Microsoft's decision to publish top-secret computer code was the best way to meet its demands in a long-standing anti-trust case.

"It's the quality of the information that counts and not the quantity," said commission spokesman for competition issues, Jonathan Todd.

The US software giant offered on Wednesday to license some of the basic binary language underpinning the company's near-ubiquitous Windows operating system in hope of satisfying the EU competition watchdog.

"They could give us half a million pages but if it's not the good information for competitors to make Windows compatible ... then it doesn't comply with the remedy," the commission spokesman said.

After eight years of conflict with European Commission, the company sought to put to rest the main technical issues in the bitter standoff.

But lawyers for competitors immediately dismissed the move as a "public relations ploy" on the grounds that lines of code were of little use without the broader "specifications" to interpret them.

The EU competition watchdog fined the software group in March 2004 a record 497 million euros (588 million dollars) for abusing its dominant market position.

It also ordered Microsoft to market a version of its Windows operating system unbundled from its Media Player software and to divulge information about its operating system needed by manufacturers of rival products.

However, the EU executive, increasingly impatient for evidence of compliance, turned up the heat in December by threatening to slap a daily fine of up to two million euros (2.37 million dollars).

Microsoft's general counsel Brad Smith said Wednesday that the company had provided as much as 12,000 pages of documentation in hope of satisfying EU regulators, but still the commission wanted more proof of compliance.

"The source code is the ultimate documentation," Smith said.

"It should have the answer to any questions that remain."

However, EU competition commissioner Neelie Kroes -- who was informed of the decision only minutes before Microsoft went public with it -- said in reaction from the World Economic Forum in Davos, Switzerland she was unconvinced.

"Normally speaking, the source code is not the ultimate documentation of anything, which is precisely the reason why programmers are required to provide comprehensive documentation to go along with their source code," Todd quoted her as saying.

Microsoft's rivals dismissed the move as only a small step towards making it easier to write Windows interoperable software on technical and legal grounds.

Free Software Foundation Europe said the offer was a "poisoned apple" because it raised copyright problems for rival programmers.

"How exactly are developers supposed to write interoperable software without looking at the source code if the specifications are not available?," said FSFE president Georg Greve.

"If you eat from that apple, you find yourself poisoned by their copyright."