'It's important to note that in this case and in others, the leaked usernames and passwords were not the result of a breach of Google systems,' Google said in its blog post. The leak does not appear to have been the result of a Gmail security vulnerability, and not all of the leaked email addresses were Gmail addresses - although the bulk were. The leak was first publicized in Russian online forums and media, including the popular technology website CNews, early Wednesday and then on a Reddit discussion forum.

Google said the leak was one of several so-called credential dumps - the posting of lists of usernames and passwords online - that the company spotted this week.

'We've protected the affected accounts and have required those users to reset their passwords.' 'Our automated anti-hijacking systems would have blocked many of those login attempts.' the post said. Google, which operates the Gmail email service, said in a post on its Online Security Blog that less than two per cent of the username and password combinations posted online 'might have worked.' We've protected the affected accounts and have required those users to reset their passwords.

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