The European Commission has laid out specific antitrust concerns it has about Vista, Microsoft’s long-awaited new operating system, commission spokesman Jonathan Todd said Wednesday.

"We are concerned about the possibility that Vista will include software elements which are available separately either sold by Microsoft or by other software companies," Todd said.

"There is also the possibility that we won’t have all the technical information needed for competitors to make their software interoperable with Vista," he added.

The commission said it told Microsoft about these concerns in a letter sent last week to Chief Executive Officer Steve Ballmer.

Microsoft declined to comment on the letter, which it said it hasn’t yet received.

The concerns echo the findings in the commission’s 2004 antitrust ruling against Microsoft, which found Microsoft guilty of bundling its Media Player software into the Windows operating system. It also ruled that the software giant had stunted competition by not allowing competitors the information needed to make their servers interoperate with PCs running Windows.

The concerns about Vista, which is due to go on sale to consumers at the beginning of next year, include plans to bundle in an Internet search function, a digital rights management program and software for creating a fixed document format comparable to the PDF format, and security features, Todd said.

"The commission is concerned that computer manufacturers and consumers won’t have a proper choice of software," he said.

Microsoft responded with a statement saying, "We have a responsibility to make our products better and more secure for our customers in a manner that respects all laws and competition standards."

"Microsoft is building Windows Vista to provide the most secure personal computing environment and to provide unprecedented opportunities for other companies throughout the industry," it continued, adding that consumers are "free to use a wide range of competitor products, and Windows Vista is designed to respect the choices that consumers make."

Microsoft said it has included partners and competitors in its planning of Windows Vista, to allow them to build products and services that work with the new operating system.

Keeping the industry and regulators informed of its product development plans "has been, and will remain a priority," Microsoft said.

No formal investigation has been opened yet, but Todd said, "If our concerns are confirmed and we conclude that Vista violated European competition rules, then we would open a new case."

Todd was responding to questions prompted by comments made by Competition Commissioner Neelie Kroes in an interview in The Wall Street Journal Europe Wednesday.