A security breach at a company that sells accounting software to the adult industry, has allowed hackers to gain access to the subscriber lists of various adult websites, including their email addresses.

New Jersey-based Too Much Media supplies an administrative software program called NATS, which is reportedly used to power the back-end of 35 to 40 percent of all adult subscription-based websites.

Essentially, the software tracks referrals to porn websites from other sites, and calculates how much the affiliate sites are owed. The porn suppliers typically pay the affiliates a portion of their subscription revenue.

The breach was first reported just before Christmas on the "In Corruption We Trust" blog, by Keith Kimmel, who has two adult websites and uses the software. Kimmel said tens of thousands of users' personal data may have been accessed.

"From what we have determined so far, whoever has done this was only seeking to harvest email addresses for spam," John Albright, the co-founder of Too Much Media, told the Washington Post.

Subscribers to adult websites, who would not rather have their identities known, are now being bombarded with junk emails advertising sexually explicit images from competitors. No credit information has apparently been stolen.

It is believed that hackers stole addresses and passwords from Too Much Media’s computers, which allowed them to log onto its customers' porn websites as the webmasters, and extract information about porn subscribers and the websites that referred them.

The pornographic industry is widely credited with the commercialisation of the Internet back in mid-1990s, but customer privacy is traditionally fiercely guarded, due to the sensitive nature of the material on view.

The breech comes at a time when the adult industry is struggling to adapt to the piracy threat to their content from peer-to-peer video sharing websites. These free websites are also being blamed for falling sales of adult DVDs.

Too Much Media did not respond at the time this news was published.