Microsoft's antitrust settlement offer to the European Commission needs changes to restore fair competition to the market for Internet browsers, said some of the software giant's main rivals. Their concerns about the settlement are echoed by ECIS, a trade group representing Oracle, IBM, Red Hat and others, as well as by consumer organisations following the Microsoft antitrust case.

Microsoft has proposed that Windows operating systems should show users a ballot screen inviting them to choose a Web browser from among the most popular ones when they first attempt to access the Internet. Consumer organisations and the company's rivals generally approve of the idea, but believe the way Microsoft's ballot screen is designed is biased and will deter people from replacing Microsoft's Internet Explorer browser with another.

They also argue that a review period two years after the settlement would come into force is too long to wait, and they call for regular monitoring of the ballot screen every six months, to make sure it is having the desired effect of encouraging consumers to exercise their free choice.

Opera, a Norwegian browser maker, Google with its Chrome browser, and Mozilla, maker of Firefox, the closest competitor to Microsoft's Internet Explorer, are all on the point of submitting their formal response to the settlement offer, and all three agree on some small but crucial problems with the Microsoft offer.

Kroes said she expects some objections to the latest Microsoft offer from some rivals. "A number of people are never 100 percent satisfied," she told journalists last month. But for her the offer is enough.

"The ballot screen is a good solution and we support it, but there are some warts, things that can easily be fixed," said HÃ¥kon Wium Lie, the chief technology officer of Opera, the company that sparked the antitrust case two years ago by complaining to the EU Regulator. The ballot screen as devised by Microsoft warns users more than once of the risks they are taking by attempting to open a non-Microsoft software product. Opera wants the warnings scrapped, allowing for a one click route to replacing Internet Explorer.

It also objects to the design of the ballot screen, with its Internet Explorer branding in the crucial top left corner of the screen. It also calls for the order of the five ballot screens to be scrambled, instead of the browsers being listed alphabetically from left to right.

The order of browsers on the screen is a big issue for Mozilla, which could find itself in the least desirable right side of the screen if the list remains in alphabetical order by company name.

ECIS is expected to take a tougher line in its response, due in with the antitrust officials by Monday.

"Experience in the EU and the US has unfortunately demonstrated that anything less than a robust settlement agreement accompanied by effective compliance verification measures will likely lead to inadequate changes in Microsoft's behavior and a failure to redress damage resulting from many years of abusive practices," one person close to ECIS said, reading from a draft of the group's formal reply to the Commission.