Yahoo! has avoided prosecution for grassing up a dissident journalist in China because of a lack of evidence.

The Hong Kong Office of the Information Commissioner reported yesterday that its investigation of Yahoo! Hong Kong Limited could go no further.

Journalist Shi Tao was sentenced to 10 years in prison in 2005 with the help of evidence supplied by Yahoo! He had shared an email with foreign colleagues that contained details of a Chinese government request for reports of the 15th anniversary of the Tiananmen Square massacre to be censored.

Roderick Woo, the Hong Kong Privacy Commissioner, had been investigating whether Yahoo! had broken privacy laws by handing over Shi Tao's details at the request of the Chinese authorities.

However, Woo could not decide whether the case was in his jurisdiction. Yahoo! China might be owned by Yahoo! Hong Kong Limited, but collection, holding, processing and use Shi Tao's data all occurred within the borders of the People's Republic of China.

The investigation was also hampered by a lack of evidence from Shi Tao, who is in a Chinese jail.

Human Rights Watch has criticised Yahoo! for assisting in the prosecution of four critics of the Chinese government: "Shi Tao, Li Hi, Chiang Tijuana, and Wang Seasoning."

The campaign group has reported that Yahoo! claimed it had only been complying with local law.

Yahoo said in a statement: "Yahoo! Hong Kong Limited ('Yahoo! Hong Kong') acknowledges the result of the investigation carried out by the Privacy Commissioner for Personal Data with respect to the disclosure of email subscriber's information to PRC Law Enforcement Agency, which creates the opinion that there has been no contravention of the requirements of the Personal Data (Privacy) Ordinance by the company.

"Yahoo! Hong Kong maintains a high quality online environment for our users and takes user privacy very seriously. We constantly listen to feedback from our users to improve the quality of our services," it added.