LinkedIn Corp is working with the FBI as the social network for job seekers and professionals investigates the theft of 6.4 million member passwords, the company said on Thursday.
The company does not know of any accounts that were taken over as a result of the security violations, according to LinkedIn spokesman Hani Durzy.
A spokeswoman with the FBI declined to comment.
LinkedIn is still in the early stages of the investigation. Durzy said it was not yet determined whether the e-mail addresses that corresponded to the hacked passwords were also stolen.
On Wednesday, LinkedIn confirmed that millions of passwords were stolen.
The company said on Thursday it would disable passwords that had been compromised and force customers to reset them.
The company sent affected members e-mails explaining how to change their passwords.