Microsoft has filed copyright infringement lawsuits against two Chinese electronics retailers.
The Windows Phone maker claims that Gome Electrical Appliances and Buynow allowed desktops and laptops with pirated versions of the Windows operating system to be sold from their stores.
The company has gone after the two Chinese firms in separate court cases filed in Beijing and Shanghai, PC World reports.
Microsoft said in its lawsuit against Gome that the retailer's store in Shanghai sold PCs that contained pirated versions of Windows and Office software platforms installed on them. The company also alleges that two retailers at a PC market run by Buynow also sold systems with pirated Microsoft software.
"Gome and Buynow's practices are unfair to retailers selling authorized software, and also bring security risks for customers," Yu Weidong, Microsoft China's senior director of IPR issues, said in a statement.
"We hope that the lawsuit will serve as a warning call for computer distributors and sellers to respect intellectual property rights," the executive added.
China is the biggest market for counterfeit software, with 78 percent of PCs running pirated versions of Windows and Office.