As the European Commission drafts guidelines urging government departments throughout the European Union to choose software based on open standards, a trade-group study published Wednesday shows that a quarter of recent public tenders have effectively excluded open software in favor of named software makers such as Microsoft.

OpenForum Europe (OFE), a trade group that lists IBM and Google among its members, examined 136 recent calls for tender by government offices from the 27 member countries of the E.U. and found that 34 of them cited brand names and half of these named Microsoft or specific Microsoft products.

"Public authorities not only stand accused of wasting potentially billions by inefficient purchasing, but also locking their users and citizens into today's solutions and being unable to take advantage of new innovation in the future," said Graham Taylor, OFE's chief executive.

The use of trademarks in public calls for tender discriminates against other suppliers and contractors and is prohibited by E.U. public procurement laws, except in some exceptional cases.

OFE is calling on the European Commission, the E.U.'s executive body, to take action to stop the naming of suppliers in public tenders, Taylor said. He pointed out that Commission research had similar findings -- a study of 3,616 public tenders found that 567, or 16 percent, named known software manufacturers. Of these, 36 percent named Microsoft, OFE said in its statement.

The OFE call for action to stop the practice comes as the Commission tries to draft guidelines that will steer government offices as they put out calls for tender for software contracts.

The guidelines are currently being finalized, but they are expected to urge public procurement officers to favor open standards wherever possible.

Some member states are simultaneously drafting their own guidelines that go even further. The Dutch government earlier this year urged government departments to use open-source software wherever possible, for example.