Bangalore: European Union (EU) antitrust regulators have opened an investigation into whether Microsoft is complying with a 2009 ruling which ordered it to offer users a choice of web browsers. The body even threatened Microsoft with fines which could be in billions of dollars.

The investigation was launched when Norwegian browser maker Opera accused Microsoft of manipulating the battle for browser share by tying Internet Explorer (IE) to Windows. The settlement required Microsoft to display a screen in Windows that provide the users with links to other browsers like Firefox, Opera, Safari and Chrome. It also demanded Microsoft to show the links in the upcoming Windows 8.

Almunia, the Head of EU said that the links are not displayed since the launch of Windows 7 Service Pack 1 in February 2011. Although the screen is available in Windows XP, Vista and original version of Windows 7, around 28 million Europeans had been affected by non-availability of choice of other browsers in this blunder by Microsoft.

Microsoft immediately apologized and said that it was a ‘technical error’. It has fixed the error on July 2 and the update would reach all the affected EU users by the end of this week.

According to the EU law, the fine could be 10% of the annual revenue which is nearly $7.3 billion considering Microsoft’s revenue last year which was $73 billion.

Almunia said it was the first time that the Commission had dealt with a case in which an offender was suspected of failing to meet its commitments under antitrust rulings.