Microsoft has suffered a setback in its endeavour for Office Open XML (OOXML) to become an alternative to OpenDocument Format (ODF) as a standard of the International Committee for Information Technology Standards (INCITS).

The software giant failed by one vote to get the necessary backing from INCITS for OOXML last Thursday.

Acceptance by the International Committee for Information Technology Standards (INCITS) is critical for Microsoft in the US. The software company has already gained approval in principle from the International Organization for Standardization (ISO), but it needs INCITS approval to keep up the momentum.

It failed to gain acceptance for Office Open XML (OOXML) on Thursday by the slimmest of margins. Eight votes were cast in favour, with seven against and one abstention, one vote short of the nine votes needed.

The result is the latest setback for Microsoft in its long-running battle to see its Open XML approved as an open standard for office documents on equal terms with OpenDocument Format (ODF).

The discussions within INCITS have been controversial. Last month, questions were raised over the membership of the crucial V1 technical sub-group of INCITS when it emerged that the group had ballooned from seven voting members at the start of the year to 26.

The vote was split along familiar lines: Intel, HP, EMC and Apple voted in favour of OOXML, while Sun's allies, such as Oracle and IBM, lined up against it. Sun had no vote.

US government bodies were split, with the US Department for Homeland Security backing Microsoft and the US Department of Defense voting against. IEEE, a large international standards body, abstained.

INCITS now has until 2 September to make its final decision as to whether it will support Office Open XML.

Colin Barker reported for ZDNet UK from London