A Chinese antitrust regulator said on Tuesday it is investigating whether Microsoft's Windows operating system and Office business suite are a monopoly. The unexpected probe comes amid an investigation of chipmaker Qualcomm's monopoly status.

Analysts said the measures targeting the US tech giants underline China's concern over technological dependency on the United States.

The State Administration for Industry and Commerce said in a statement that Microsoft's two iconic products were reported by other companies for compatibility and file verification failures because Microsoft did not disclose enough product information. Microsoft is also facing tied-in sale investigations, the SAIC said.