Microsoft's reluctance to make its Office suite interoperable with competing products has prompted a British government agency to complain to the European Commission, which is already investigating the company's conduct in this area.

The British Educational Communications and Technology Agency (BECTA) filed a complaint with the UK Office of Fair Trading last October, and has now forwarded it to the Commission, it said late Monday. The complaint alleges that Microsoft's behaviour impedes the exchange of files between Office 2007 and competitors' products, and that its licensing practices in the market for software for schools are anti-competitive.

BECTA's renewed complaint comes just days after Microsoft announced it would appeal an €899 million ($1.3 billion) fine the Commission imposed in February to punish Microsoft for failing to provide timely and adequate information about the interoperability of its workgroup server products, as the Commission had ordered in a March 2004 anti-trust ruling.

The Commission opened two new anti-trust investigations against Microsoft in January, one concerning the interoperability of Windows with other software, and the other concerning Microsoft's tactic of bundling software products with its Windows operating system.

As part of the first of those two investigations, the Commission said it will look at whether the Office Open XML document format used by Microsoft Office is sufficiently interoperable with competitors' products. BECTA has now sent its complaint and evidence to support that investigation, it said.

Impediments to interoperability can limit software buyers' choice, tying them to one vendor's applications. In the market for education software, this can result in higher prices, and have an impact on links between work in schools and work done at home, BECTA warned.