Global press leaders on Tuesday told China to stop Internet censorship and free all detained cyber-dissidents, and they slammed Western companies that helped it develop software that prevents Chinese citizens from accessing information on human rights and democracy.

They called on China “to end its pervasive censorship of the Internet, release all journalists and cyber-dissidents currently detained and remove all restrictions that discourage an open and free media environment in the country.”

Members of the International Press Institute (IPI), a global body of editors, leading journalists and media executives, unanimously adopted the firm line at their annual general assembly in the Scottish capital Edinburgh.

China has the second-largest number of online users in the world after the United States, with more than 130 million Chinese accessing the Internet, said the institute dedicated to press freedom.

But as the web has grown in popularity, the Chinese authorities have maintained control over information.

“The Chinese government is working closely with Western companies eager to enter the lucrative Chinese technology market to develop software that prevents Chinese citizens from accessing information on human rights and democracy,” the IPI resolution said.

“Those companies should not cooperate with censorship and should not supply information about users that can be used to prosecute journalists.”

The IPI said that at least 30 people were in Chinese jails on freedom of expression charges.

These include Ching Cheong, a journalist with Singapore’s Straits Times newspaper, who faces espionage charges, and New York Times researcher Zhao Yan.

“IPI members are convinced that progress in China is undermined by the state’s cynical exploitation of Western technology, unnecessary legislation and encouragement of self-censorship,” the resolution said.

Internet search engine Google raised eyebrows in January when it launched its new service for China, google.cn, after agreeing to censor websites and content banned by the nation’s propaganda chiefs.

Delegates in Edinburgh heard Sunday that Google had the choice between delivering the vast majority of information that it could, in line with local laws, or not operating in China at all.

Google principle scientist Krishna Bharat said: “As an information provider, denying people information does not seem like a good choice.”

The IPI’s three-day congress brings together some 450 participants from 60-odd countries to debate burning issues for the world’s press.