China operates a broad-based net filtering system
Australian government plans to filter net use have been rebuffed by local internet service providers (ISPs).
Telstra, Australia's largest ISP, has said it will not join trials of the filters and others say they will only back a scaled-down system.
The government wants to filter all net traffic and block access to 10,000 sites deemed to hold illegal content.
The initial trials of the filtering technology were due to take place before Christmas.
Australian newspaper The Age reports that both Telstra and Internode have declared they will not participate in the trials. iiNet said it wanted to take part to show that the filters do not work and Optus would only work with a scaled back plan.
The plan to set up mandatory filters followed research by the Australian Communications and Media Authority which found that existing filters did a poor job of blocking illegal content.
Responding to the rebuff by ISPs, Australia's communications minister Stephen Conroy said the initial trials would not be "closed" and involve no actual customers.
Optus said it would take part in the trial in early 2009 but would only impose filters that blocked access to a 1300-strong list of sites hosting illegal content.
It said it would not block access to the full 10,000 sites demanded by the Australian government nor impose the second tier of filtering that blocks sites unsuitable for children.
Politicians for Australia's Green party called on the government to abandon the filtering plan which has been widely criticised.
Protests are expected on 13 December in Sydney and Melbourne calling for an end to the scheme.