GUANGZHOU - Investigators have cracked an online copyright-infringement case involving the software giant Microsoft, police here said on Tuesday.

Economic-crimes investigators received a complaint from Microsoft alleging that a host of various websites in Zhaoqing, a city in Guangdong province, had infringed on one of the company's copyrights. In response, officials established a task force in August, according to He Guangping, deputy head of the Guangdong provincial department of public security.

Investigators found the server for those websites, the most famous of which is jujumao.cn, in Zhaoqing.

"After investigating, police discovered that the principal suspect, whose surname is Wang, established jujumao.cn in 2003 and later registered other websites to let netizens download pirated versions of Microsoft's Windows XP and Windows 7 for free," he told a news conference in Guangzhou, capital of Guangdong, on Tuesday.

"Wang illegally earned a large sum of money by bundling the pirated software with advertisements and other software."

In 2011 alone, pirated versions of Windows software have been downloaded 4,445 times from Wang's websites, he said.

"We've been encouraged by the Zhaoqing police's successful crackdown on online pirate groups," said a Microsoft statement on Tuesday.

"We see opportunities for continued improvement on intellectual property protection in China and we are hopeful they will lead to meaningful and lasting results."

Yao Xin, chief representative of the Business Software Alliance, a Washington-based trade group, praised the police for fighting copyright infringements.

Since October 2010, the Zhaoqing police have investigated 20 cases of suspected copyright infringement amid a national campaign to eradicate such violations.

"In recent years, China has done more to protect intellectual property rights," said Feng Xiaoqing, a law professor at the China University of Political Science and Law.

"They (the efforts) have effectively curbed rampant copyright violations and provided protection to overseas companies' interests in China."