Communication Minister Stephen Conroy said Tuesday that the Australian filter targets material such as child pornography, bestiality, rape and other sexual violence, along with detailed instructions about committing crimes or using illicit drugs.
Late Tuesday, Fiona Patten of the Australian Sex Party said that the filter would block 95 percent of adult websites and slow down the web dramatically.
"How your can have a filter blocking access to more than 4 million sites with more than 420 million pages and not slow the Internet down is beyond belief," she said.
While the filter would not likely not be in place before early in 2011, critics contend that the mandatory screening system would make Australia one of the strictest Internet regulators among the world's democracies.
Authoritarian regimes commonly impose controls. Countries such as China, Egypt and Iran impose strict Internet controls.
Obscene material already is banned from publication on Australian websites, but the government currently has no control over it being accessed on servers overseas.
Critics also say illegal material, including child pornography, often is traded on peer-to-peer networks, which would not be covered by the filter.
"The government knows this plan will not help Australian kids, nor will it aid in the policing of prohibited material," said Colin Jacobs, vice chairman of Electronic Frontiers Australia, a nonprofit group that advocates public-interest rights in the digital space.
Conroy's announcement Tuesday coincided with the release of a report that found Internet service providers were able to block a list of more than 1,300 sites selected by the government without significantly hampering download speeds.
Australia's largest Internet service provider, Telstra, said blocking offensive sites using a filter system was feasible as long as the list was limited to a defined number of web addresses, but that no single measure would make the web free from illegal material.