The news site Gizmodo said its analysis showed little if any activity from the purported 5.5 million female members of Ashley Madison, who were online with an estimated 31 million male subscribers.

“The more I examined those 5.5 million female profiles, the more obvious it became that none of them had ever talked to men on the site, or even used the site at all after creating a profile,” editor Annalee Newitz wrote.

In fact just three in every 10,000 Ashley Madison members are real women, it has been revealed, as the huge scale of fake female accounts on the infidelity website was exposed.

Detailed personal information on millions of users was leaked in the hack, including credit card numbers and sexual preferences.

The lawsuits were filed by people who had signed up to Ashley Madison in California, Texas, Missouri, Georgia, Tennessee and Minnesota.

They all seek class-action status to represent all registered Ashley Madison users.

The lawsuits, which seek unspecified damages, claim negligence, breach of contract and privacy violations.

They claim Ashley Madison failed to take reasonable steps to protect the security of its users, including those who paid a special fee to have their information deleted.

Ashley Madison is offering a $500,000 reward for information leading to the arrest of a group that hacked the site.

Gizmod said the leaked data suggests the vast majority of profiles of women on Ashley Madison were fake, or created by automated “bots”.

The data showed 20 million men had checked messages on Ashley Madison, compared with only 1,492 women. For the chat system, 11 million men logged on but only 2,409 women did so, Gizmodo found.

Further strange details included the fact that the most popular female last name in the database was “an extremely unusual one”

The hackers who took responsibility for the break-in accused the website’s owners of deceit and incompetence, and said the company refused to bow to demands to close. The hackers called themselves the Impact Team.