There has been a dramatic rise in the number of people detained or sentenced for internet-related offences in China, according to the London-based rights group Amnesty International.
Around 80 million people are online in China
There are now at least 54 people who have been imprisoned for emailing, setting up websites or exchanging pro-democracy messages online - a 60% increase from a year ago - the group said in its latest report on the repression of internet users by the Chinese authorities.
In addition, an unknown number of people remained in detention for disseminating information over the internet about the spread of the Sars virus.
Many of the individuals cited in the report have been denied due process of law and some have been tortured or ill-treated in custody, says Amnesty.
The report detailed a 35% expansion in internet access in China in the past year, with the number of users rising by from 59 million in December 2002 to almost 80 million by the end of 2003.
"As use of the internet grows, so the Chinese authorities have introduced further measures to control access to it," said the report's author, Louise Vischer.
China is believed to extend greater censorship over the internet than any other country in the world.
New legislation means that all 110,000 internet cafes must now use a particular form of software that will control access to websites considered harmful or subversive - including those of Amnesty itself, the BBC, and other international human rights groups, news and non-governmental organisations.
Thousands of special police are also employed to patrol the cafes and to monitor websites and email exchanges, Amnesty's Louise Vischer told BBC News Online.
She believed the large number of people signing petitions and joining forums on the internet was a reflection of the growing need felt by the young in China to express themselves.
"And there seems to be a strong sense of solidarity among them," she said.
"For instance a woman called Liu Di was detained for a year for discussing issues such as political reform and for calling for the release of a fellow internet dissident.
"Her detention in turn resulted in many more petitions and more arrests.
"But whether the government will win the battle in the end is anyone's guess," she said.