The State Administration for Industry & Commerce (SAIC) said on Tuesday that it is conducting an anti-monopoly investigation into Microsoft Corp.

The SAIC said in a statement posted on its website that it is carrying out the probe because the firm has not fully disclosed information about its Windows operating system and Microsoft Office software, confirming widespread speculation that Microsoft might be caught up in an antitrust probe in China.

The regulator is currently investigating a Microsoft vice president and senior managers, and has made copies of the firm's financial statements and contracts.

The SAIC, which is in charge of market supervision and regulation, usually takes the lead in bribery and corruption investigations as well as intellectual property rights abuse cases.

The government agency called up nearly 100 law enforcement officials from nine provinces and municipalities including Beijing, Shanghai, South China's Guangdong Province and Southwest China's Sichuan Province to visit the software giant's four offices in the Chinese mainland without informing the company in advance, according to the statement.

The regulator has obtained documents, e-mails and other data from Microsoft's computers, servers, and impounded two work computers, it said, adding that it could not complete the investigation as Microsoft had said some of its key personnel were not in China.

A response from Microsoft to the SAIC's statement was not available when contacted by the Global Times on Tuesday. But Reuters reported Microsoft repeated what it had said on Monday that it had been visited by officials and that the company was "happy to answer the government's questions," citing a statement by Microsoft.

Microsoft has already engaged a Chinese law firm to help with the anti-monopoly case, said the law firm, declining to be identified or to comment any further.

The SAIC statement verifies media reports on Monday that the US software titan might be another foreign company to fall under the oversight of the Chinese government which has ramped up efforts to crack down on monopolistic behaviors.

Qualcomm Inc, the world's biggest mobile chip maker, is facing penalties that may exceed $1 billion in one such Chinese antitrust probe, following accusations of overcharging and abusing its market position.

In 2013, officials from SAIC visited large international drug manufacturers in China including AstraZeneca Plc and Sanofi SA, as part of a broad investigation into the sector. SAIC officials also visited the Hangzhou office of Roche Holding AG earlier this year.

The latest move by China's authorities also caps a rocky period for Microsoft in the country.

In May, central government offices were banned from installing Windows 8, Microsoft's latest operating system, on new computers. This ban appears to not have been lifted, as multiple procurement notices since then have not allowed Windows 8.

Nevertheless, the company has pushed forward with plans to release its Xbox One gaming console in China in September, forming distribution ties with wireless carrier China Telecom Corp and e-commerce company JD.com Inc.