Labor's plan to protect children from online pornography and graphic violence has been backed by family groups, but dismissed by the government and internet industry.

Opposition Leader Kim Beazley said a Labor government would force internet service providers (ISPs) to block violent and pornographic material before it reached home computers.

Under the "clean feed" system, pioneered in Britain, users would be unable to access any content banned by the Australian Communications and Media Authority (ACMA) because it contained graphic sexual or violent material, rated R or higher.

He said the current system, which required ISPs to offer all subscribers cheap or free filter software for their own computers, was not working.

"The reality is that cost and poor computer literacy mean almost two-thirds of parents don't have internet filters on their family computers," Mr Beazley said.

"That is not good enough when research suggests that the exposure of children and others in the community to this sickening content can lead to aggression towards women and child abuse."

Communications Minister Helen Coonan said PC-based internet filters, which ISPs must offer to subscribers at a cheap price, were better and had been taken up by more than one in three families using the net.

"PC-based filters are more effective at blocking all manner of offensive content, provide greater control to parents of the content their children are exposed to and do not affect the performance of the internet for all users," Senator Coonan said.

She said a recent study by internet safety body NetAlert found the kind of filtering proposed by Labor could slow connection speeds by up to 78 per cent without being as effective as a filter on a home computer.

"We know we have to let our kids roam the internet for study, yet we can't be watching over their shoulders all the time to monitor what they are seeing."

However, Internet Industry Association executive director Peter Coroneos said the current system in Australia, which involved three enforceable codes of practice, was world-class.

"A family who takes advantage of (filter programs) will have a far greater degree of confidence in limiting the kind of material their children are likely to access than would occur if we adopt the limited clean feed model."

The ACMA is currently auditing the top 25 ISPs, which cover about 95 per cent of internet users in Australia, for compliance with the codes of practice.

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