European Union regulators in Brussels said Thursday they will consider Microsoft Corp.'s promise to make its Office productivity programs work more seamlessly with competing software.

Microsoft said Wednesday it would update Office 2007 to allow users to save text, spreadsheets and other documents in the portable document format — as PDF files — and other non-Microsoft file formats, in addition to its own Office Open XML format, known as OOXML.

The changes, due next year, would add the formats — including a competing standard called OpenDocument Format created by open source developers and used by IBM Corp., Sun Microsystems Inc. and others — as defaults consumers could choose from for saving all their documents.

Microsoft's announcement was the latest in a series of moves meant to show it has changed its ways and is no longer the same company whose anti-competitive behaviour provoked more than $2.63 billion US in fines in the EU.

Critics have remained skeptical of Microsoft's vows to make its software work better with rival programs, and European regulators opened two new Microsoft antitrust investigations in January, one related to the OOXML format.

"In its ongoing antitrust investigation concerning interoperability with Microsoft Office, the commission will investigate whether the announced support of ODF in Office leads to better interoperability," the European Union's executive arm said Thursday.

Critics who support ODF say Microsoft is trying to supplant ODF with OOXML and lock users into buying Office programs forever, stemming the threat of open source software eating into its market share.

Despite a chorus of complaints, OOXML was approved last month as an international standard, paving the way for it to be used by the IT departments of governments and large corporations.

Microsoft said Wednesday it continues to work with the open source community on an OOXML-ODF translator.

The Redmond, Wash.-based software maker said the changes will be made with Office 2007 Service Pack 2, expected in the first half of 2009.