Victims allegedly included 124 civil servants, 92 Ministry of Defence staff, around 50 police officers, 56 NHS workers, 65 local education and school staff and 1,716 people at universities and further education colleges.
The data contained addresses, ages, phone numbers, credit card details and even sexual fantasies of users.
Ashley Madison has said it is working with police forces to find the hackers and has offered a $380,000 reward for any information leading to their arrest.
"We are actively cooperating with international law enforcement in an effort to bring those responsible for the theft of proprietary member and business information to justice," Avid Life Media said.
A series of negative stories have emerged since the hack on Ashley Madison, which was set up in 2001 with the slogan: "Life is short. Have an affair."
It was claimed that only around 12,000 of the 5.5m women signed up to the website are real, while the vast majority are fake profiles created to lure in male subscribers.
An investigation by technology website Gizmodo allegedly found that many of the IP addresses connected to female users could be traced back to Ashley Madison itself.
The report also revealed that 20m men had checked their messages on the site, compared with just 1,492 women.
Meanwhile, 11m men logged on to use the website's chat function compared with just 2,409 women who also checked their messages.
The company was sued in 2012 by former employee Doriana Silva, who claimed she was told to create more than 1,000 fake profiles in order to attract paying customers. Her lawsuit claimed this caused her to develop repetitive stress injury and she was unable to work since. Ashley Madison countersued, alleging fraud. The Ontario Superior Court dismissed the case without costs earlier this year, a result which the company was "very pleased" with, according to Avi Weisman, vice-president and general counsel for Avid Life Media.
The company is now facing a $578m class-action lawsuit by Charney Lawyers and Sutts, Strosberg LLP, two Canadian firms representing users who accuse the company of failing to sufficiently protect their private data. The firm charged around £12 for a service in which it promised to remove a user's personal data from its servers.
It also emerged that Ashley Madison planned to launch an app that allowed users to rate each others' wives, Daily Dot reported.
The app, which was given the working title of "What's Your Wife Worth", places a dollar amount next to the picture depending on how attractive they are.
According to Daily Dot, Mr Biderman sent an email commenting on the idea. "Choice should be 'post your wife' and 'bid on someone's wife,'" he allegedly wrote, adding: "I am not sure we should be asking for real names - rather usernames."
However, the app was never finished.
While the company has attracted anger from around the world for encouraging people to cheat on their partners, the hacking and subsequent fallout has raised the question of whether the identities of those who signed up to the site should be revealed.
At least two clients may have committed suicide and others have become the victims of extortion, Canadian police said earlier this week.
"This hack is one of the largest data breaches in the world and is very unique on its own in that it exposed tens of millions of people's personal information including their credit card data," said Bryce Evans, staff superintendent with the Toronto police. "This is affecting all of us. The social impact behind this leak, we're talking about families, we're talking about children, we are talking about wives, their male partners."
Meanwhile, the first British divorce to arise from the leak has begun. Nigel Shepherd, a partner at the family law firm Mills & Reeve, revealed that a married woman had contacted after discovering her partner's details among the millions of leaked accounts.
He told The Times: "If someone finds out if their partner is set up on a site which exists wholly for facilitating adultery, it's hardly surprising they are taking advice about it."
Chris Longbottom, head of family law at Shoosmiths, said that his firm had received around three calls a day since the hackers made their demands last month and said he was expecting many more now that the information had been published.
Relate, the relationship counselling service, also revealed that it had started to take calls from worried individuals who had discovered their partners' details in the data.
Ashley Madison did not immediately return requests for comment.
- Daily Telegraph UK
