Competition Commissioner Neelie Kroes of the European Commission has given her strongest statement to date in favour of software based on open standards, in a speech that took Microsoft to task over its competition practices.

"No citizen or company should be forced or encouraged to choose a closed technology over an open one," Kroes said at a conference in Brussels, according to reports.

She said open standards are also in line with profitable business decisions. "I know a smart business decision when I see one — choosing open standards is a very smart business decision indeed," she said.

The conference at which she spoke was organised by OpenForum Europe, which advocates open standards.

The Commission is engaged in an ongoing competition dispute with Microsoft, which has included handing the software company two record fines.

While Kroes did not mention Microsoft by name, she referred to the two fines. "The commission has never before had to issue two periodic penalty payments in a competition case," Kroes said.

The Commission has not yet satisfied itself that Microsoft is complying with measures designed to make it easier for competitors' software to interoperate with Windows desktop operating systems, the cause of the two successive fines.

Regarding the interoperability question, Kroes took exactly the line espoused by open source companies, which is that interoperability protocols guarded by Microsoft are not trade secrets, as Microsoft argues.

"Where interoperability information is protected as a trade secret, there may be a lot of truth in the saying that the information is valuable because it is secret, rather than being secret because it is valuable," she said.

In a veiled criticism of Microsoft's OOXML document format, she criticised the inclusion of proprietary technology in standards.

"I fail to see the interest of customers in including proprietary technology in standards when there are no clear and demonstrable benefits over non-proprietary alternatives," she said.

Kroes said there are security concerns associated with relying on a single, dominant software supplier, and warned against the long-term dangers of software vendor lock-in.

"We need to be aware of the long-term costs of lock-in: you are often locked-in to subsequent generations of that technology," she said. "There can also be spillover effects where you get locked in to other products and services provided by that vendor."

She praised efforts such as those of the City of Munich to develop a desktop environment to replace Windows, and urged "vigorous" support of a 2007 EC policy that promotes the use of software based on open standards.