By Vanessa Mock

BRUSSELS--European Union competition chief Joaquin Almunia on Tuesday announced a major probe into Microsoft Inc. (MSFT), to investigate whether the firm failed to meet earlier obligations to allow users easy access to other web browsers.

Mr. Almunia vowed to move fast with a "very rigorous investigation" into whether the software giant failed to properly implement a demand by EU regulators to offer users a choice screen allowing them to choose their preferred web browser.

Using unusually strong language, Mr. Almunia said if the case is confirmed, he would "use all legal instruments with all the capacity to deter and to punish." If confirmed, it would be the first time a company has flouted earlier commitments, he said. The move could see the company face hundreds of millions of euros in fines.

"We take compliance with our decisions very seriously. And I trusted the company's reports were accurate. But it seems that was not the case," Mr. Almunia told reporters in Brussels. "If, following our investigation, the infringement is confirmed, Microsoft should expect sanctions."

If found guilty, Microsoft could face a maximum fine of 10% of its turnover.

The case relates to a legally binding commitment Microsoft undertook in 2009 to offer so-called remedies in a long-running competition probe into the dominance of its client PC operating system.

"This is in my view a very important case to ensure all the citizens and all the companies operating in the market that competition law requires a real serious enforcement," Mr. Almunia said.

Write to Vanessa Mock at vanessa.mock@dowjones.com

Microsoft (NASDAQ:MSFT)
Historical Stock Chart
From Mar 2024 to Apr 2024 Click Here for more Microsoft Charts.
Microsoft (NASDAQ:MSFT)
Historical Stock Chart
From Apr 2023 to Apr 2024 Click Here for more Microsoft Charts.