Yu Zhang, the Director of Chinese Independent PEN Centre's Writers in Prison Committee, has formally complained Yahoo for its alleged part in the conviction of Chinese journalist and poet Shi Tao, the Guardian reports.

The complaint "alleges that Yahoo Hong Kong provided information about the email account used to send the memo without Shi's consent. This information was crucial to the Chinese government's case against Shi."

Hong Kong legislator Albert Ho told the Associated Press that it was "very clear from the judgment that Yahoo Hong Kong provided the details", while Yu adds that "the key to establishing Yahoo's involvement is found in article four, which refers to 'account holder information furnished by Yahoo Holdings (Hong Kong) Ltd', and gives details of the telephone number and address associated with the account holder."

Though Yahoo's counter-argument is that they were complying with local law, Yu disputes this. "They're a Hong Kong company. Why do they have to comply with Chinese requests?"