July 21, 2015 - Hackers have breached the systems of Ashley Madison, a dating website for would-be adulterers, and are threatening to publish the personal information, including credit card transaction details, of millions of users.

The hackers, calling themselves the Impact Team, posted a notice on Ashley Madison's website claiming to have "taken over all systems in your entire office, and production domains, all customer information databases, source code repositories, financial records, emails".

The message, since removed but captured by security blogger Brian Krebs, demands that the site's owner, Avid Life Media, shut down Ashley Madison and another site called Established Men.

The hackers appear to have taken the action over a service the cheating site claims to offer which allows its 37 million users to completely delete their profiles for a fee of $19. The Impact Team says that the site does not actually perform a "full delete".

If the sites are not shuttered, the hackers are threatening to "release all customer records, profiles with all the customers' secret sexual fantasies, nude pictures, and conversations and matching credit card transactions, real names and addresses, and employee documents and emails".

Avid Life Media has issued a statement saying: "At this time, we have been able to secure our sites, and close the unauthorized access points. We are working with law enforcement agencies, which are investigating this criminal act. Any and all parties responsible for this act of cyber-terrorism will be held responsible."