It has also opened new avenues for corruption and cronyism. A series of regulatory attacks on Google in recent years had the side effect of making its chief rival, Baidu.com, the prime internet gateway for China's 338 million internet users. Baidu now boasts 63 per cent of Chinese search traffic compared with Google's 31 per cent, according to Analysys International.

Google, like all internet service providers in China, is required to self-censor political content according to rules that are deliberately vague and arbitrarily enforced.

The keyword filtering was performed by a Google joint venture company, which was tasked with responding to specific demands from officials from a range of departments, regions and tiers of government and even businesses - many of which were in competition with each other.

Google had already declined to set up a China-based ''.cn'' version of its Gmail system in order to avoid the predicament that its competitor Yahoo faced in 2004 of being legally required to hand over personal user details to Chinese authorities.

Yesterday Google said it would no longer censor its China search engine service, which almost certainly means the service will be shut. The service continued in its censored form yesterday, as Google is anxious to avoid exposing 600 employees at Haidian, in Beijing's university district, to legal and security repercussions that could result if it continued to maintain the uncensored product illegally.