Professional social networking site LinkedIn has confirmed that some of the 6.5 million passwords reportedly leaked from the company match those of its users.

Earlier today, it was reported that a file containing 6.5 million partially encrypted passwords from LinkedIn appeared on a Russian cyber criminal website. 

"We can confirm that some of the passwords that were compromised correspond to LinkedIn accounts," the company said, after many hours of investigating the claims.

The company has automatically changed the passwords of affected accounts and users will receive an email with instruction on how to reset their passwords.

Security experts had criticised LinkedIn for apparently not ‘salting’ its customers passwords, a method of encryption that is harder to break. The company said in its latest update that it had introduced password salting "just recently".

"We sincerely apologize for the inconvenience this has caused our members," the company said. "We take the security of our members very seriously."

Earlier today, LinkedIn offered users advice on how to keep their accounts secure.