Internet giant Google is warning many users of its popular Gmail service that they may be the target of state-sponsored cyber attacks.

The California-based company unveiled a new warning system Tuesday to alert Gmail users when it suspects “state-sponsored” attackers are attempting to compromise their accounts or computers using malicious software.

Many China-based Gmail users reported received the warning early Wednesday in the form of a banner message at the top of their email accounts. The warning also reportedly appeared on accounts in the U.S. and Japan.

Google said in a blog post the appearance of the warning does not necessarily mean that the account has been hijacked, but that it may be a target. The company urged account holders to create a strong password and take a number of other security procedures to ensure protection.

Google says it cannot provide details on how it knows that specific attacks are government-sponsored. But it said “detailed analysis” and “victim reports” strongly suggest the involvement of governments or state-sponsored groups.

Although Google did not mention any specific governments that may be behind the attacks, many technology analysts suggest it may be another chapter in the long-running dispute between Google and China over censorship and web privacy issues.

The announcement comes days after Google took a veiled swipe at Beijing's massive Internet censorship network. Google said last week it would begin alerting users when they type a search term likely to be blocked in mainland China.

Last week's announcement was careful not to mention Chinese government censors. But it said searching for such terms often causes error messages and temporary disconnections, wryly noting that Google engineers have “taken a long, hard look at our systems and have not found any problems.”

Google has in the past blamed China for cyber attacks. Last year, the Internet giant accused China-based hackers of breaking into the email accounts of hundreds of people, including senior U.S. officials, journalists, and Chinese political activists.

Google complained of a much wider cyber attack by Chinese-based hackers in 2010, which led it to move the servers of its popular Chinese search engine to Hong Kong.

Though the move outside mainland China meant Beijing could not fine-tune Google search results, the government still censors material by blocking results for terms that it considers harmful or subversive.