A 2012 LinkedIn data theft may have affected far more users than originally thought, the professional networking site said, adding that it was working to reset passwords of millions of accounts.

LinkedIn said in a statement that it was working to invalidate the passwords of some 100 million accounts after it "became aware of an additional set of data that had just been released that claims to be email and hashed password combinations of more than 100 million LinkedIn members from that same theft in 2012."

It said it was "taking immediate steps to invalidate the passwords of the accounts impacted, and we will contact those members to reset their passwords. We have no indication that this is as a result of a new security breach."

More than 6 million member passwords were stolen when LinkedIn was hacked in 2012. – Reuters