Almost 5 million Gmail usernames and passwords surfaced on Wednesday on a Russian Bitcoin forum, said a report published on The CNBC.

The report quoted The Daily Dot as saying that most of the data was old and outdated. Majority of the accounts have been suspended or cannot be matched to old passwords.

The leak appears to have been collected via hacking and phishing over a period of time, according to the report.

In a statement, Google said, "The security of our users' information is a top priority for us. We have no evidence that our systems have been compromised, but whenever we become aware that accounts may have been, we take steps to help those users secure their accounts."

Users are urged to change their passwords often and enable two-step verification to their accounts.