The identity of a Mississauga man who was registered on infidelity website Ashley Madison was one of the first two profiles to be leaked online following a hack of the service’s estimated 37 million users.

In a letter circulating online, hackers calling themselves The Impact Team released the name, home address and profile of the Mississauga man, along with information belonging to another man in Brockton, Massachusetts.

The hackers released intimate details of the users’ profile, including their listed sexual fetishes and fantasies.

The hackers said the Mississauga man had recently paid Ashley Madison a “full delete” fee to remove his information entirely.

In the letter, The Impact Team threatens to release the identities of all 37 million users of the site unless its parent company, Avid Life Media, shuts the site down entirely.

“Avid Life Media has been instructed to take Ashley Madison and Established Men offline permanently in all forms, or we will release all customer records, including profiles with all the customers' secret sexual fantasies and matching credit card transactions, real names and addresses, and employee documents and emails,” the letter reads.

In a statement released July 20, Avid Life Media insists the “full delete” fee “does in fact remove all information related to a member’s profile and communications activity.” The firm will allow any registered to erase their information from the site for free.

Avid Life Media had earlier said it had wiped all references to user’s personal information from the Internet.

"Nothing is private, you’re always at risk when you have any information about yourself on the Internet," said Kenneth Owen, a cybersecurity expert and PhD candidate at McMaster University.

"You have to accept that it is possible, that no matter what you do, whatever you have out there will be found if someone wants to find it."