Millions of Gmail passwords 'hacked'

Five million Gmail addresses and passwords appeared on a Russian Bitcoin forum on Wednesday despite denials by Google of a security breach.

Little is known about the origin of the details, with CNN reporting they could be a collection of passwords exposed in previous hacks, likely on users’ own computers and not Google’s systems.

"We have no evidence that our systems have been compromised," Google spokeswoman Caroline Matthews said.

The company also said there was no evidence the list is even authentic.

As a precaution, Google has locked all of the email accounts included in the leak, directing affected users to a website to reset their password and regain access to their account.

Google has also advised all Gmail users to create stronger passwords and use an extra security feature called two-step authentication.