The URLs of some 2395 websites purported to be banned under the Australian Communications and Media Authority's blacklist were leaked to Wikileaks this morning.
Late this afternoon, Senator Stephen Conroy said that while the leaked list has "some common URLs to those on the [ACMA] blacklist," it also contains URLs that "have never been the subject of a complaint or ACMA investigation and never been included in the ACMA blacklist."
"This is not the ACMA blacklist," he said.
"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."
Anthony Pillion, managing director of Webshield, one of six ISPs participating in the Federal Government's internet filtering trial also said "there is a giant question mark over the motive and credibility of the content in the leak".
Pillion said the leaked list was not a list of URLs in use during the trials.
"It seems as if it is a compilation of information available on the web, and includes some URL's never investigated by ACMA," he said.
"That makes it questionable at least."
"It has more basis in michief than in credibility."
Conroy said the leak and publication of prohibited URLs was "grossly irresponsible."
"The ACMA blacklist includes URLs relating to child sexual abuse, rape, incest, bestiality, sexual violence and detailed instruction in crime," he said.
"No-one interested in cyber-safety would condone the leaking of these addresses."
If the domain names in the list are any guide, most of the URLs sighted by iTnews appear to link to content that could be deemed objectionable under the law.
The list also includes some of Australia's largest gambling sites, such as BetFair and Full Tilt Poker, and links to a Queensland dentist and a Queensland dog kennel.
Pillion said that, assuming some of the URLs are of child abuse material, he would consider it "pretty poor form for somebody to want to make that information publicly available".
An online story in a Sydney newspaper earlier today attributed the leak without qualification to a Government-approved maker of internet filtering products.
Pillion doubted those companies would leak the information.
"The only motive could be somebody that dislikes intensely what the Government is proposing at the moment, and will go to any lengths to undermine it."
For the past two years, ACMA has sent weekly updates of its lists to makers of internet filters, Pillion said: "There would have to be copies of various lists floating around".
The lists used in filtering trial are encrypted and "far more secure", he said.
Conroy expects that an ACMA investigation over the leak may lead to a "referral to the Australian Federal Police."
"Any Australian involved in making this content publicly available would be at serious risk of criminal prosecution," he said.
Online rights advocate, Electronic Frontiers Australia, said the list confirmed some of its worst fears about filtering.
"This was bound to happen, especially as mandatory filtering would require the list to be distributed to ISPs all around the country," said EFA vice-chairman Colin Jacobs.
"The Government is now in the unenviable business of compiling and distributing a list which includes salacious and illegal material and publicising those very sites to the world."
Jacobs told iTnews that he guessed some of the more innocuous sites on the list may have had their web servers hacked.
"Those sites may have been used to distribute inappropriate material," he said.
"The website operator may have fixed the site but found there is no way to get off the blacklist."