LUXEMBOURG (AP) – A British watchdog agency said Tuesday it had complained to European Union regulators that Microsoft Corp.’s new file format for storing documents discouraged competition.

Britain’s agency for education and information technology said it wanted to feed information into an investigation the EU launched in January. That investigation is looking at whether the software giant deliberately withheld information from rivals that the rivals wanted so they could make their products compatible with Microsoft software.

This comes on the heels of EU antitrust action against Microsoft Corp. that has already resulted in US$2.63 billion (euro1.7 billion) in fines.

The watchdog, the British Educational Communications and Technology Agency, said it had told the European Commission that barriers to interoperability – which would allow different software products work smoothly with each other – hurt students and teachers.

”Impediments to interoperability limit choice,” the agency said. ”In the context of the education system, this can result in higher prices and a range of other unsatisfactory effects.”

In an e-mailed statement, Microsoft spokeswoman Anne-Sophie de Brancion said the corporation would cooperate with both the British watchdog agency and the European Commission.

”Microsoft is deeply committed to education and interoperability,” the statement said. ”We believe that more and more schools are upgrading to Windows Vista and Office 2007 as they increasingly recognize the benefits of embracing technology to transform teaching and learning. We have funded the development of tools to promote interoperability between Office 2007 and products based on the ODF (OpenDocument Format) file format.”

The watchdog agency was passing on to the European Commission – the EU executive – a complaint it initially filed in October with Britain’s Office of Fair Trading. That complaint objected to ”the existence of impediments to effective interoperability in relation to Microsoft’s 2007 product.”

This referred Microsoft’s new file format, Office Open XML, which stores Word, Excel and PowerPoint files.

Critics of Office Open XML, or OOXML, claim it locks out competitors, giving Microsoft customers no choice but to keep buying Microsoft programs forever. Microsoft claims its format is a more useful and varied alternative to another open standard, OpenDocument Format or ODF, which is backed by Sun Microsystems, IBM and others.

The British agency said that problems using Office 2007 software would be compounded by Microsoft’s refusal to offer the same support to users of OpenDocument Format that it gives to Office Open XML.

”This decision had the effect of requiring (OpenDocument Format) users to download and install a range of converters to enable them to interoperate with those competitor products,” it said. ”Such circumstances would constitute a barrier to the uptake and use of competitor products and limit competition and choice for educational users.”

The agency complained that OpenDocument Format converters are ”poorly integrated into the overall Microsoft user interface as compared with for example the integration and functionality Microsoft offers for its own OOXML format.”

The agency also said British regulators were still looking into its complaint about Microsoft’s license conditions for school software, where the agency alleged ”anticompetitive licensing practices.”

It wants the Office of Fair Trading to look at other software used with Windows to check whether there are any other barriers to competition and choice – and take action if necessary.

In 2005, the British watchdog agency said primary schools could save up to 50 percent and secondary schools up to 25 percent if they dumped proprietary software – like Microsoft’s – in favor of free, or open source, products.

The Redmond, Washington-based company is one of the largest software suppliers to British schools.