Google says computer hackers in China broke into the Gmail accounts of several hundred people, including senior government officials in the U.S. and political activists.

"This campaign, which appears to originate from Jinan, China, affected what seem to be the personal Gmail accounts of hundreds of users including, among others, senior U.S. government officials, Chinese political activists, officials in several Asian countries (predominantly South Korea), military personnel and journalists," Google said in a statement

"The goal of this effort seems to have been to monitor the contents of these users’ emails, with the perpetrators apparently using stolen passwords to change peoples’ forwarding and delegation settings."

Google says all victims have been notified and their accounts have been secured.

"It’s important to stress that our internal systems have not been affected — these account hijackings were not the result of a security problem with Gmail itself," Google said. "But we believe that being open about these security issues helps users better protect their information online."

The attacks announced Wednesday on Google's blog aren't believed to be tied to a more sophisticated assault originating from China in late 2009 and early last year. That intrusion targeted Google's own security systems and triggered a high-profile battle with China's Communist government over online censorship.

The tensions escalated amid reports that the Chinese government had at least an indirect hand in the hacking attacks, a possibility that Google didn't rule out.

In the latest incident, Google believes Chinese hackers tricked people into sharing their passwords in so-called "phishing" scams.