China’s anti-trust watchdog has asked Microsoft Corp. to explain “major issues” that it says have cropped up in an investigation over the software giant's alleged violation of China’s anti-monopoly law, according to local media reports.

Regional executives of the Silicon Valley titan have been asked to respond to inquiries over data obtained as part of the investigation, China’s State Administration of Industry and Commerce (SAIC) reportedly said Tuesday.

SAIC did not specify exactly what issues it was investigating, but the request appeared to be part of an investigation into Microsoft over its Windows operating system launched in mid-2014, Reuters said. The SAIC move comes more than a year after the investigations were first launched.

Microsoft has been teaming up with another U.S.-based software maker Computer Sciences Corp. to tap China's government procurement market selling its Windows 10 operating system,  according to state-run ChinaDaily news.

In August, the SAIC questioned Microsoft's lawyer Mary Snapp after formally investigating the software giant and raiding four of its offices in China, Reuters reported. When the investigation was first launched, SAIC had said Microsoft had not fully disclosed information about Windows and its Office software suite. 

"We're serious about complying with China's laws and committed to addressing SAIC's questions and concerns," a Microsoft spokesman told Reuters. The company’s shares were down marginally during pre-market futures trading in New York.

The  U.S. chipmaker Qualcomm Inc. was fined 6.1 billion yuan ($975 million) by the Chinese regulator in February, 2015, after finding the company had violated anti-monopoly  laws .