"We have evidence to suggest that a primary goal of the attackers was accessing the Gmail accounts of Chinese human rights activists," said Drummond, who added that with the exception of two accounts, those attacks had been unsuccessful. The message content of those accounts was not compromised, Drummond claimed; instead, only some information, such as subject lines and the date the account was created, was accessed.

Drummond also said Google had discovered that the Gmail accounts of dozens of U.S.- and Europe-based advocates of human rights in China had been "routinely" accessed by unauthorized users.

"We have taken the unusual step of sharing information about these attacks with a broad audience not just because of the security and human rights implications of what we have unearthed, but also because this information goes to the heart of a much bigger global debate about freedom of speech," said Drummond.

Google launched its Chinese-language search engine at google.cn in early 2006, and at the time on business in the country. "We will carefully monitor conditions in China, including new laws and other restrictions on our services. If we determine that we are unable to achieve the objectives outlined we will not hesitate to reconsider our approach to China," the .

The disturbing nature of the attacks, as well as what Drummond called "attempts over the past year to further limit free speech on the Web" by Chinese authorities, gave the company pause, then led it to a decision.