Microsoft will address the European Union's antitrust concerns about users' ability to chose between different browsers in upcoming Windows 8 operating system.

Almunia is in charge of antitrust enforcement at the European Commission.

"In my personal talks with Microsoft CEO Steve Ballmer he has given me assurances that they will comply immediately regardless of the conclusion of the anti trust probe," European Commissioner Joaquin Almunia said at a conference in northern Italy, Reuters reported on Saturday.

Almunia did not said how Microsoft would address the regulator's concerns.

Last Jule, EU antitrust regulators initiated an investigation on whether Microsoft blocks computer makers from installing web browsers other than its Internet Explorer (IE) on its upcoming Windows 8 operating system.

The issue is part of an investigation into Microsoft's failure to offer users a choice of rival web browsers in its Windows 7 OS, which it had agreed with regulators three years ago.

The EU watchdog is also looking into allegations that Microsoft does not provide access to complete interfaces (APIs) for non-default browsers in Windows 8.

The investigationalso focuses on charges that Microsoft allows only its own Internet Explorer browser to be installed on devices running Windows 8 on Windows RT tablets with ARM chips.

Windows 8 is due out October 26.