TORONTO » Two Canadian law firms have filed a $578 million class-action lawsuit against the companies that run Ashley Madison after a hacker group’s data breach exposed some 39 million memberships in the adultery website earlier this week.

Charney Lawyers and Sutts, Strosberg LLP, both of Ontario, said Friday that they filed the lawsuit on behalf of Canadians who subscribed to Ashley Madison and whose personal information was disclosed to the public. The website, with its slogan "Life is short. Have an affair," is marketed to facilitate extramarital relationships.

The lawsuit, filed Thursday in the Ontario Superior Court of Justice, targets Avid Dating Life Inc. and Avid Life Media Inc., the Toronto-based companies that run AshleyMadison.com. Its class-action status "still needs to be certified by the court," the statement says.

Ashley Madison did not immediately respond to requests for comment. It has said that the personal details exposed in the initial data leak can’t be used to prove the infidelity of their clients.

The plaintiff is Eliot Shore, an Ottawa widower. Shore said he joined the website for a short time in search of companionship after he lost his wife to breast cancer. He said he never cheated and never met up with any members of the site.

Lawyer Ted Charney told The Associated Press it is the first class-action suit filed against the companies in Canada.

In the U.S., Missouri lawyers have filed a class-action lawsuit in U.S. District Court seeking more than $5 million in damages. Lawyers filed a statement of claim late last month on behalf of an unnamed female plaintiff who said she ponied up $19 so Ashley Madison would purge her personal information from its website in a process called a "paid-delete."

The lawsuit argues that the privacy of Canadian members was breached in July when hackers infiltratedAshley Madison’s website and downloaded private information. The data breach includes users’ personal names, emails, home addresses and message history. On Tuesday, the information was posted publicly online.

The law firms’ statement said numerous former users of the website have approached them to inquire about their privacy rights under Canadian law.

"They are outraged that AshleyMadison.com failed to protect its users’ information. In many cases, the users paid an additional fee for the website to remove all of their user data, only to discover that the information was left intact and exposed," lawyer Ted Charney said.

"The sensitivity of the information is so extreme and the repercussions of this breach are so extreme, it puts the damages faced by members in a completely different category of class-action suits," said Charney.

The law firms said the lawsuit is not being brought against the hackers, who have said they attacked the website in an effort to close it down as punishment for collecting a fee without actually deleting users’ data.

The law firms did not immediately respond to a request for comment, and it was not clear in what court the class-action lawsuit was filed.

There are hundreds of email addresses in the data release that appear to be connected to federal, provincial and municipal workers across Canada, as well as to the Royal Canadian Mounted Police and the military.

According to the data breach, some of the website’s customers made credit-card transactions from computers attached to the Department of National Defense and Canada’s House of Commons.

The data, stored in more than 2,500 files, involved transactions spanning from March 2008 to several days in June of this year.

National Defense referred most questions to the federal Treasury Board, which has an overall responsibility.

Lisa Murphy, spokeswoman for the Treasury Board, would only say that the government has rules for the professional and personal use of its computers.

In a written statement, a DND spokeswoman echoed some of Murphy’s statement, and said the department "has policies and practices in place to deter, detect and enforce unauthorized and prohibited computer use."

The credit-card information of U.S. government workers, some with sensitive jobs in the White House, Congress and the Justice Department, was also revealed in the data breach.