Compromised sites include video sex-chat site and Adultfriendfinder
A photo illustration shows the Ashley Madison website displayed on a smartphone in Toronto, August 20, 2015. REUTERS/Mark Blinch

Login credentials of millions of people who used adult friendship sites have been compromised in the largest online hack of the year.

The latest adult site data dump includes 63 million records from video sex-chat site The overall number of people whose identities face the risk of being unraveled amounts to 412 million.

The compromised accounts are all from various sites run by California-based FriendFinder Networks Inc, Reuters reported. The sites include, and adult magazine site, the agency reported citing LeakedSource.

FriendFinder said it is in the process of notifying affected users to provide them with information and guidance on how they can protect themselves.

"Our investigation is ongoing but we will continue to ensure all potential and substantiated reports of vulnerabilities are reviewed and if validated, remediated as quickly as possible," FriendFinder said.

If the leaked information is accurate the number of affected people will be ten times higher than those exposed in the hacking of infidelity website Ashley Madison last year.

Among the latest data dump are email addresses with the .mil domain, showing as many as 78,301 US military personnel used their official addresses to join the adult friendship and cheating sites.