But, as experts have long warned the government, having a top-secret blacklist of banned sites is dangerous because there is a real danger that Australian businesses could be added to the list in error, with little recourse. Inevitable leaks of the list, as happened today, mean those innocent businesses' websites could be associated with child porn repositories.

"Any person or corporation that would be identifiable on the list would potentially be deemed by the general public ... either a child molester or at least in the same category as child molesters," said University of Sydney associate professor Bjorn Landfeldt. "In effect, this could be interpreted by some as a government sanctioned hate list. "Even if the list is not leaked directly, it may be possible to reverse engineer the list and find out its content."

Alongside child porn, bestiality, rape and extreme violence sites, the list also includes a slew of online poker sites, YouTube links, regular gay and straight porn sites, Wikipedia entries, euthanasia sites, websites of fringe religions such as satanic sites, fetish sites, Christian sites, the website of a tour operator and even a Queensland dentist. Other Australian sites on the list are canteens.com.au ("Tuckshop and Canteen Management Consultants") and animal carers MaroochyBoardingKennels.com.au.

The dentist, Dr John Golbrani, was furious when contacted to inform him that his site, dentaldistinction.com.au, appeared on the blacklist. "A Russian company broke into our website a couple of years back and they were putting pornographic listings on there ... [but] we changed across to a different web provider and we haven't had that problem since," Golbrani said in a phone interview. He said the fact that he hadn't been removed from the list was "criminal" and he was scared potential customers may avoid him.

"The government needs to get in and clean it up," said Golbrani. Jocelyn Ashcroft, who runs a school canteen consultancy in Queensland, also said she had no idea why her site had made it on to the blacklist.

"The only thing I can think of is that I have emailed schools telling them about my book and CD resource How to Have a Healthy and Profitable Theme Day," she said "This is targeted specifically at schools and I send each email individually. There is no software involved in this process, just me copy and pasting." Daniel Purser, who runs a web hosting and web design company out of NSW called Startcorp, was also shocked to learn that his site had been blacklisted.

He said there was "no chance" any of his customers were hosting child porn or other questionable content. "We only host our own customers that we've done designs for and most of them are referrals from our own customers or referrals from my family," he said.

"Our service provider in Australia wouldn't tolerate it either, they've got a very definite anti-pornography rule. "Obviously somebody needs to have a look at the list and actually make an assessment on whether it's a legitimate complaint or not because obviously no investigation has been done at all." Colin Jacobs, spokesman for online users' lobby group Electronic Frontiers Australia said: "The prospect of mandatory nation-wide filtering of this secret list is pretty concerning from a democratic point of view."

UPDATE: The Minister for Broadband, Communications and the Digital Economy, Senator Stephen Conroy, has this afternoon denied that the list of banned websites published on Wikileaks is the ACMA blacklist. "The published list purports to be current at 6 August 2008 and apparently contains approximately 2400 URLs whereas the ACMA blacklist for the same date contained 1061 URLs," he said in a statement.

"There are some common URLs to those on the ACMA blacklist. However, ACMA advises that there are URLs on the published list that have never been the subject of a complaint or ACMA investigation, and have never been included on the ACMA blacklist." The list on Wikileaks is understood to have been obtained from an internet filtering software maker. The disparity in the reported figure is most likely due to the fact that the list contains several duplicates and variations of the same URL that stem from a single complaint. Alternatively, some sites may have been added to the list by the filter software maker.