A database of what appears to be some 5 million login and password pairs for Google accounts has been leaked to a Russian cyber security internet forum. It follows similar leaks of account data for popular Russian web services.

The text file containing the alleged compromised accounts data was published late on Tuesday on the Bitcoin Security board. It lists 4.93 million entries, although the forum administration has since purged passwords from it, leaving only the logins.

The accounts are mostly those of Google users and give access to Gmail mail service, G+ social network and other products of the US-based internet giant. The forum user tvskit, who published the file, claimed that 60 percent of the passwords were valid, with some users confirming that they found their data in the base, reports CNews, a popular Russian IT news website.

Google Russia said it is investigating the alleged leak, adding that it advises customers to use strong passwords and enable two-step login verification to protect their accounts.

The leak comes just days after similar leaks affected Mail.ru and Yandex, both popular Russian internet services. The previous leaks contained 4.66 and 1.26 million accounts respectively.

Both companies said that an overwhelming majority of the accounts listed were either obsolete, suspended for suspicious behavior or non-existent. They insisted that their own databases were not compromised and suggested that the leaked data was accumulated over years through phishing and other forms of hacking attacks on users.