Google is warning account holders it believes are targets of state-sponsored attacks.
Affected accounts would have a forboding banner message splashed across Google web sites.
However how it determined that hackers were state-sponsored was privy only to Google: Disclosing such information including its “detailed analysis” and victim reports would assist “bad actors”, it said.
"Warning: We believe state-sponsored attackers may be attempting to compromise your account or computer."
“We believe it is our duty to be proactive in notifying users about attacks or potential attacks so that they can take action to protect their information,” Google said in a blog post
Google has been quick to finger Chinese state-sponsored hackers for previous attacks. It blamed such hackers for launching the 2010 Operation Aurora attacks against it and a string of high profile companies including Adobe and Juniper Networks.
And in June last year the company claimed to have stopped a sophisticated attack from Chinese actors that targeted human rights activists, government officials and journalists.