Microsoft said Wednesday it had opened an investigation following a report of harsh working conditions at a factory in China that makes products for the US software giant.

The Pittsburgh-based National Labor Committee (NLC), in a report released Tuesday, denounced conditions at a KYE Systems Corp factory in Dongguan, in Guangdong Province.

The NLC, a private group with a stated mission to "help defend the human rights of workers in the global economy," said KYE recruits hundreds of "work study students" aged 16 and 17 years old who work 15- hour shifts, six and seven days a week.

It said that in 2007 and 2008, before the recession, "workers were at the factory 97 hours a week while working 80-and-a-half hours."

"In 2009, workers report being at the factory 83 hours a week, while working 68 hours," the NLC said. Workers were paid 65 cents an hour.

"Workers are prohibited from talking, listening to music or using the bathroom during working hours," the NLC report said, adding that "as punishment, workers who make mistakes are made to clean the bathrooms.

Microsoft said it took the claims "seriously" and vowed to "take appropriate remedial measures in regard to any findings of vendor misconduct."

Shang Rong, Chief Public Relations Officer of Microsoft China Research & Development Group, told the Global Times, "Microsoft has established a management mechanism with our vendors."

Shang didn't mention the detailed rules of management for the factory.

Meanwhile, the company has invited an independent third-party auditing program to ensure conformance to the Microsoft Vendor Code of Conduct, Shang added.

"Microsoft is committed to the fair treatment and safety of workers employed by our vendors," AFP quoted the Redmond, Washington-based company, as saying in a statement.

The NLC report said the factory makes computer mice for Microsoft, as well as products for other companies, including Hewlett-Packard, Best Buy, Samsung, Foxconn, Acer, Logitech and Asus.