The details were apparently taken when LinkedIn was hacked four years ago
A hacker claiming to have more than one hundred million LinkedIn logins is advertising them for sale online.
The extensive list of user IDs and passwords were allegedly sourced from a cyber attack on the networking site four years ago.
According to news site Motherboard, a hacker calling himself "Peace" has placed the alleged details of 117 million LinkedIn users on "dark web" marketplace The Real Deal for the price of 5 Bitcoin - the digital currency - worth around £1,500.
In the wake of the 2012 breach, only around 6.5 million details were posted online - but LinkedIn's chief information security officer Cory Scott said he does not believe the extra data was gained as the result of a new security breach.
"In 2012, LinkedIn was the victim of an unauthorised access and disclosure of some members' passwords," he said.
"We are taking immediate steps to invalidate the passwords of the accounts impacted, and we will contact those members to reset their passwords," he said.