BEIJING - Baidu, China's search engine giant, was blamed Tuesday by Chinese writers for participating in copyright violations, since the website offers free online excerpts of unauthorized stories and books.

On March 15, which is World Consumer Rights Day, more than 40 writers said in an open letter that Baidu stole their work and infringed on their copyrights.

The letter was published on the personal blog of Shen Haobo, a publisher, and called for an end to the piracy.

Fang Zhouzi, a well-known writer, told Xinhua that he could find almost all of his works on Baidu's online library. Even a book published 10 years ago was scanned and uploaded to the Internet.

"We hope to arouse attention from law enforcement authorities and to combat copyright thieves on the Internet," he said.

China Written Works Copyright Society also issued a statement on its website on Tuesday, urging all publishing companies and writers to jointly sue Baidu.

This was not the first time that Baidu has been criticized for violating copyright laws.

Similar complaints surfaced last November from online publisher Shanda Literature Corporation (SDL), which owns more than 80 percent of the country's online literary publications as well as the seven leading original Chinese literature websites.

More than 1.1 million authors had signed contracts to provide Shanda with original works. However, pirated versions were commonly found in Baidu search results.

Pirate websites, which could easily be found on Baidu, profited by charging lower reading fees than the official sites and from advertising links.

Baidu's cooperation towards Internet piracy leads to over one billion yuan of losses to the SDL every year, according to Shanda CEO Hou Xiaoqiang.

Shanda said Baidu's "lenient" attitude towards piracy had transformed Baidu's online library into a hotbed for on-line copyright theft.

Launched in November 2009, Baidu's online library offers an open platform for online resource sharing. Users can read or download information for free, and all accumulated resources come from user uploads.

In the past year, it has stocked more than 10 million documents.

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Baidu admitted that some Internet users could upload pirated content, but insisted that this only accounted for a small part of the whole library.

Facing Shanda's censure, Baidu said that it would actively introduce copyrighted works, as well as charges for online literature, to solve the copyright issue.

But the writers did not see any improvement in Baidu before they released their open letter to protest the piracy issue.

Song Huixian, an expert on China's Copyright Protection Center, said that the intellectual property issue was hard to avoid on the Internet.

He urged authorities to set up better mechanisms to not only promote the effective spread of information on the Internet, but also protect the interests and rights of copyright holders.

In this year's government work report, Premier Wen Jiabao said that "we will intensify our efforts to crack down on violations of intellectual property rights and the manufacture and sale of counterfeit or substandard goods."