Microsoft has stepped up its fight against software piracy in China with unprecedented lawsuits against Chinese electronics retailers.

The company is suing Shanghai Gome, a branch of one of the country’s largest electronics and appliances chains, and Beijing Chaoyang Buynow, one of China’s largest computer malls. Microsoft said in a statement dated January 5 that it had evidence that pirated copies of Microsoft Windows and Microsoft Office were pre-installed in computers sold by the two stores.

The move comes after the US technology group said last week that it was taking legal action against Comet, the UK electrical appliances retailer, in connection with the sale of recovery CDs for Windows products to consumers who had bought computers at its stores. The company has denied any wrongdoing.