China appeared to cave in to public pressure Tuesday by announcing that computer users are not required to install internet filtering software — though it will still come with all PCs sold on the mainland.

A Ministry of Industry and Information Technology official reached by telephone told The Associated Press that use of the Green Dam Youth Escort software is "not compulsory." He would not give his name as is customary with Chinese officials.

The government had said the new software must be packaged with all computers sold in China beginning July 1. It was widely believed that users would be required to install the software, although the government did not explicitly say so.

However, the ministry official and state media both said Tuesday that computer users are free to decide whether to use the new software.

The apparent reversal of the government's position marked a small victory for a burgeoning anti-censorship movement in China. Internet users in particular have expressed growing frustration with official efforts to monitor and restrict online content.

Although the government says the software is aimed at blocking violence and pornography, users who have tried it say it prevents access beyond those topics to discussions of homosexuality, images of comic book characters, mentions of the banned Falun Gong spiritual group and, according to Hong Kong media reports, images of pigs because the software confuses them with naked human flesh.

Public outcry

"The government is clearly responding to public pressure," said Yang Hengjun, 45, a well-known blogger and novelist based in the southern city of Guangzhou. "People, including myself, have argued strongly that while parental controls are useful, picking which one to use must be a personal choice."

The regulation had sparked public outcry, with lawyers, bloggers and academics formally challenging the mandate with lawsuits and petitions while average internet users viciously mocked it.

Green Dam is just the latest attempt to rein in China's increasingly lively internet forums.

China already has the world's most extensive system of web monitoring and censorship and has issued numerous regulations in response to the rise of blogging and other trends. Operators are required to monitor web pages and bulletin boards and delete content deemed subversive.

But controlling content has become increasingly difficult with the explosion of China's internet population, now the world's largest with 298 million users. Chinese blog authors total 162 million.

While other methods of control exist, Green Dam is the government's most intrusive tool yet because it extends censorship to the user's personal hard drive and can even force offline programs like text editors to crash if a banned phrase like Falun Gong is typed.

Security compromised

Tests of Green Dam by independent researchers have found that the software blocks a wide range of politically sensitive key words as well as pornography and also makes computers more vulnerable to security threats.

"We examined the Green Dam software and found that it contains serious security vulnerabilities due to programming errors," said the summary of a report posted on the internet by computer scientists at the University of Michigan. "We recommend that users protect themselves by uninstalling Green Dam immediately."

A number of petitions and at least one legal challenge. Beijing lawyer Li Fangping submitted a request to the Ministry of Industry and Information Technology last week demanding a public hearing on the "legitimacy and rationality" of forcing computer makers to include the software with every unit sold. Li said Tuesday he had yet to receive a response from the ministry.

Wen Yunchao, another Guangzhou blogger who posts under the name Bei Feng, said he did not consider the latest announcement a victory for Chinese internet users because computer manufacturers must still bundle Green Dam with their products and because 40 million yuan ($6.6 million) in taxpayer money has already been spent on the software.

PC makers will be required to tell authorities how many computers they have shipped with the software, which is made by a Chinese developer under contract with the government.