San Francisco ? Google Inc. will stop censoring its search results in China and may pull out of the country completely after discovering that computer hackers had tricked human-rights activists into exposing their e-mail accounts to outsiders.

The change of heart announced Tuesday heralds a major shift for the Internet’s search leader, which has said it will obey Chinese laws requiring some politically and socially sensitive issues to be blocked from search results available in other countries. The acquiescence had outraged free-speech advocates and some shareholders, who argued it violated the company’s “don’t be evil” motto.

The criticism had started to sway Google co-founder Sergey Brin, who openly expressed his misgivings about the company’s presence in China.

Hacking attacks

But the tipping point didn’t come until Google uncovered hacking attacks launched from within China. The apparent goal: gathering personal information about dozens of human rights activists trying to highlight the country’s censorship and other secretive policies.

Google officials said they plan to talk to the Chinese government to determine if there is a way the company can provide unfiltered search results in the country. If not, Google is prepared to leave China four years after creating a search engine bearing China’s Web suffix, “.cn,” to profit from the world’s most populous country.

“The decision to review our business operations in China has been incredibly hard, and we know that it will have potentially far-reaching consequences,” David Drummond, Google’s top lawyer, wrote in a Tuesday blog posting. A spokesman for the Chinese consulate in San Francisco had no immediate comment.

Abandoning China wouldn’t put a big dent in Google’s earnings, although it could crimp the company’s growth as the country’s Internet usage continues to rise. Google, based in Mountain View, said its Chinese operations account for an “immaterial” amount of its roughly $22 billion in annual revenue.

Although Google’s search engine is the most popular worldwide, it’s a distant second in China, where the homegrown Baidu.com processes more than 60 percent of all requests.

‘Bold and difficult’

Free-speech and human rights groups are hoping Google’s about-face will spur more companies to take a similar stand.

“Google has taken a bold and difficult step for Internet freedom in support of fundamental human rights,” said Leslie Harris, president of the Center for Democracy & Technology, a civil-liberties group in Washington.

Google’s new stance on China was triggered by a sophisticated computer attack orchestrated from within the country. Rep. Anna Eshoo, D-Calif., praised Google for disclosing chicanery that “raises serious national security concerns.”

Without providing details, Google said it and at least 20 other major companies from the Internet, financial services, technology, media and chemical industries were targeted. The heist lifted some of Google’s intellectual property but didn’t get any information about the users of its services, the company said. Google has passed along what it knows so far to U.S. authorities and other affected companies.

The assault on Google appeared primarily aimed at breaking into the company’s e-mail system, “Gmail,” in an attempt to pry into the accounts of human right activists protesting the Chinese government’s policies.

Only two e-mail accounts were infiltrated in these attacks, Google said, and the intruders were only able to see subject lines and the dates that the individual accounts were created. None of the content written within the body of the e-mails leaked out, Google said.

As part of its investigation, Google stumbled onto another scam that was more successful. Google said dozens of activists fighting the Chinese government’s policies fell prey to ruses commonly known as “phishing” or malware.