Microsoft yesterday surprised us all when it pledged to make its Office suite interoperable with competitors’ products by adding support for ODF, Adobe PDF and even the XML Paper Specification in a Service Pack due next year. The software giant claims the move will give consumers more choice, but European regulators aren’t convinced such is necessarily the case and thus are launching a probe on them.

The European Commission has long accused Microsoft of abusing its dominant market power by making software that is incompatible with products made by its rivals. Back in February, regulators slapped Microsoft with a record $1.3 billion fine after it defied a 2004 antitrust ruling that came with a $788 million fine. Microsoft is currently appealing against the decision.

While many welcomed the company’s new file format stance, its rivals termed the move insufficient and a delaying tactic amid an ongoing anti-trust battle opened against Microsoft in January, which targets its widely-used Office program.