A glowing report on the government's national Internet content filtering scheme has again outraged telecommunications providers and privacy advocates who declared the results biased and worthless.

ISP content filtering is part of the government's $125.8 million Plan for Cyber Safety which will split funds between law enforcement, technology and education to reduce the proliferation of child porn and inappropriate content on the Internet.

The report follows laboratory trials by the Australian Communications and Media Authority (ACMA) that began in June last year and tested six Internet content filters for accuracy and network load. Tests were set in a Telstra lab on a Tier 3 broadband network with a load of 30 simulated users.

Results showed marked improvements in the accuracy and efficiency of content filters since the previous report commissioned in 2005. However, experts say the results are not good enough for wide scale deployment.

Electronic Frontiers Association chair Dale Clapperton said the government's upcoming pilot will fail.

"We view this test as anything but successful. These filters will wrongly block access to about 3 percent of the Internet if they are forced on Australians, and while the Minister may regard this as an acceptable level of collateral damage, we do not," Clapperton said.

"The government needs to provide more information on what it wants to block access to, because it ranges from child porn to 'inappropriate material'.

"The [upcoming] trials are targeting a lot more than child pornography and illegal content."

Clapperton said the government needs to provide more information on what content will be blocked, and expressed concern that the blacklists in the trials were set to ban all material rated from R18+ to a "strong" M.

He said part of the criteria, which tested the ability of the filters to block illegal content, could be seen as an attempt to "overstate the accuracy" of the filters because the manufacturers design the technology with the blacklist built in.

"The filters couldn't even block 100 percent of content that they are designated to block by the manufacturers," he said.

Author of NetAlarmed.com,a parody Web site of the Internet filtering scheme, and Web production manager Michael Meloni said the lab trial was too small to indicate whether the filters will work at an ISP level.

"With [the 1 to 8 percent false positive rate], Australians are going to come up against quite a few blocked sites each day that should not be blocked. I don't think they will tolerate it," Meloni said.

"The Internet contains hundreds of thousands of Web sites not appropriate for children by our classification standards and we can't block them all."

The results are further tainted by the 3930 sample URLs used in the trial, according to Meloni, because the filters will have to block access to millions of Web sites.

He said the problem is exacerbated by the inability of the solutions to filter file sharing networks.

"The Internet contains hundreds of thousands of Web sites not appropriate for children by our classification standards and we can't block them all."