Microsoft has been fined 561m euros ($731m; 484m) for failing to promote a range of web browsers, rather than just Internet Explorer, to users in the European Union (EU).

It introduced a Browser Choice Screen pop-up in March 2010 as part of a settlement following an earlier EU competition investigation.

But the US company dropped the feature in a Windows 7 update in February 2011.

Microsoft said the omission had been the result of a "technical error".

But competition commissioner Joaquin Almunia said the action was unprecedented, adding he wanted to deter any company from the "temptation" of reneging on such a promise.

In theory the watchdog could have fined the firm 10% of its global annual revenue, which would have totalled $7.4bn based on its 2012 report.

"We take full responsibility for the technical error that caused this problem and have apologised for it," a spokesman for Microsoft said following the announcement.

"We provided the Commission with a complete and candid assessment of the situation, and we have taken steps to strengthen our software development and other processes to help avoid this mistake - or anything similar - in the future."

BBC News