New internet software designed to filter out violence and porn in China may not be mandatory, it has been reported.

Fears that internet filtering would be enforced across China have been allayed slightly by a Ministry of Industry and Information Technology official’s comment that the Green Dam Youth Escort software is “not compulsory”.

The anonymous official told Associated Press that although all new computers sold in mainland China will have the software already installed from 1st July, people will not be forced to install it on existing machines.

Green Dam Youth Escort has been widely criticised by anti-censorship organisations as the latest attempt by the Chinese government to restrict online freedom.

While the government claims that the software is aimed only at blocking violence and pornography, it has emerged that it also blocks discussion of homosexuality and other non-pornographic gay content. It had even been found to block pictures of pigs, mistaking the image for naked human skin.

A Ministry of Industry and Information Technology notice from May 2009 stated: “In order to build a green, healthy, and harmonious online environment, and to avoid the effects on and the poisoning of our youth’s minds by harmful information on the internet, the Ministry of Industry and Information Technology have purchases one-year exclusive rights to use “Green Dam Youth Escort” Green Online Filtering Software…. the software has been shown to effectively filter harmful content in text and graphics on the internet and has already satisfied the conditions for pre-installation by computer manufacturers.”

Despite the apparent government reversal, China still has the world’s most extensive web censorship system, aimed at removing ‘subversive’ content from websites, blogs, forums and message boards.

Green Dam Youth Escort, for instance, automatically downloads an updated list of prohibited sites from an online database, and collects private user data.

As well as censoring online content, Green Dam Youth Escort can access users’ hard drives and can crash programmes if banned words like ‘Falun Gong’ are typed.

One blogger known as Bei Feng claimed that the government has spent 40 million yuan (£3.6 billion) of taxpayers’ money on the software, which will be packaged in to every computer sold from July onwards.

However, the rate of internet use in China – there are currently around 298 million users in the country – has made internet filtering or control increasingly difficult.

In 2001, homosexuality was decriminalised in China, a move that has called for similar action in other Asian countries, while Hong Kong held its first ever Pride march in 2008, with a thousand people taking part.