Google will warn users of its online email service GMail when their account is being targeted by state-sponsored cyber attacks, the web giant announced yesterday.

The web giant already monitors accounts for unusual activity such as unauthorised login attempts and phishing email traffic. However, it will now issues warnings to "a subset of our users who we believe may be the target of state-sponsored attacks".

Writing on Google’s Online Enterprise blog, vice president of security engineering Eric Grosse said Google could not go into details about the nature of these state-sponsored attacks without "giving away information that would be helpful to these bad actors".

"Our detailed analysis—as well as victim reports—strongly suggest the involvement of states or groups that are state-sponsored," he said.

Previously, Google has pointed to China as a source of cyberattacks against its ecosystem and other Western corporations.

In 2010, it revealed that it had been the victim of a six month phishing and malware campaign, dubbed Operation Aurora. The campaign was reportedly designed to access the email accounts of "Chinese human rights activists". According to Ahsar Aziz, CEO of security monitoring company Fire-Eye, the attack was aimed at the Dalai Lama.

At the time, Google said it would be strengthening its security infrastructure and architecture, and recommended that users deploy "reputable anti-virus programs…and update their web browsers [and operating systems]".