China has deployed "colossal human and financial resources to obstruct online free expression", according to a report by two human rights pressure groups.

An investigation by Reporters Without Borders and Chinese Human Rights Defenders claimed that the Communist Party of China and the government have brought Chinese news websites and blogs under editorial control at national and local levels.

The China: Journey to the heart of Internet Censorship report (PDF) was written by a Chinese technician working for an internet company who uses the pen name 'Mr Tao'.

The document claims to outline the mechanisms used to censor the internet in China, and shows how the Internet Information Administrative Bureau controls the leading news websites.

"This system of censorship is unparalleled anywhere in the world and is an insult to the spirit of online freedom," said Reporters Without Borders and Chinese Human Rights Defenders in a joint statement.

"With less than a year to go before the Beijing Olympics, there is an urgent need for the government to stop blocking thousands of websites, censoring online news and imprisoning internet activists."

The report urges Chinese citizens to sidestep the censorship by using proxy servers, exploiting the different levels of censorship between provinces or between levels in the administration, and using new internet technologies such as blogs, discussion forums and internet telephony.

Reporters without Borders said that China now has more than 160 million internet users and at least 1.3 million websites.