The US Congressional International Anti-Piracy Caucus on Wednesday listed China as one of the world's five-worst offenders in violating copyright. The other four nations were Canada, Mexico, Russia and Spain.

But Wang Chunyan, an expert in intellectual property studies at Renmin University of China, said the nation, with an online population of 316 million, is taking on the challenges.

"We never denied it. But the government is trying its best in seeking a proper way to balance the interests of various sides and people's rights to obtain information," she said.

She was responding to criticism from the anti-piracy caucus, made up of more than 70 members of the Senate and House of Representatives, that claimed piracy of copyrighted movies, music, video games and other entertainment had reached "alarming levels" in the five countries and "cost the US copyright industries and the millions of Americans who work in these companies billions of dollars".

The group claimed the Chinese government "has permitted piracy to fully contaminate the online marketplace via an array of nefarious illegal websites, file storage sites (and) user-generated content sites."

"Despite the Chinese government's many public assurances that it is committed to combating copyright piracy, little action has been taken against infringing online activities," claimed the report.

China's largest Internet search engine, Baidu, was said to be "responsible for the vast majority of illegal downloading of music in China, deriving significant advertising revenue."

But last month China issued an IPR protection plan involving 28 ministries and organizations that had 170 concrete measures to fight copyright infringement. Also, the Supreme People's Court raised compensation for victims from 500,000 yuan ($73,000) to more than 1 million yuan ($146,000).

Last year, China closed 192 websites that profited from copyright infringement and uncovered 5719 cases of copyright infringement, Commissioner of the State Intellectual Property Office Tian Lipu said.

The World Trade Organization in March confirmed China's achievements and rejected most items of a US allegation on China's IPR protection.

As for comments about Baidu, a senior lawyer with Hong Kong-based S&F Intellectual Property cited inside sources as saying US search engine Google planned to pick up Baidu's profit model by providing free music downloading and paying copyright fees by putting up ads.