"The combination of non-democratic regimes and commercial filtering technology is especially worrying," said Ron Deibert, a political science professor at the University of Toronto and a member of the Open Net Initiative that monitors filtering globally. The group has labeled China as employing "pervasive" filtering, as well as Iran, Syria, Tunisia, Uzbekistan, Burma, and Vietnam. "We have also seen an increase in offensive forms of filtering which attack servers. ... This was observed targeting opposition groups before election time in countries including Belarus and Kyrgystan," Deibert said.
Yang Xiaokun, a Chinese government representative at the U.N.-organized Internet Governance Forum in Athens, has flatly refused to acknowledge any restrictions on the Internet in China. When confronted with reports of journalists arrested in China, he labeled them as criminals and and denied that the arrests have anything to do with the freedom of expression.
Yang Xiaokun can be excused, for, he must be unaware of the reports on Internet filtering in China, such as this one from the Open Net Initiative.