The Federal Government will introduce compulsory internet filtering to block overseas sites which contain criminal content, including child sex abuse and sexual violence.

Communications Minister Stephen Conroy announced the changes today following a controversial trial to filter the internet which was conducted earlier this year.

Senator Conroy says some internet content is simply not suitable in a civilised society.

"It is important that all Australians, particularly young children, are protected from this material," he said.

"The Government believes that parents want assistance to reduce the risk of children being exposed to such material."

He says the Government will not determine what is blacklisted on the internet in Australia, rather an independent body will determine what sites are rated as RC for refused classification.

Legislation will be introduced into Parliament next year which will require all ISPs to block material which has been refused classification in other countries.

This would include sites containing child sex abuse, bestiality, sexual violence or detailed information about how to use drugs or commit crimes.

The filtering trial attracted criticism from some who said it would not work and would slow internet speeds.

But Senator Conroy says the trial has been successful.

"Our pilot, and the experience of ISPs in many western democracies, shows that ISP level-filtering of a defined list of URLs can be delivered with 100 per cent accuracy," he said.

"It also demonstrated that it can be done with negligible impact on internet speed."

Grants will also be offered to ISPs to voluntarily block other content.

After the legislation is passed the filter will take 12 months to implement.

Criticism

But Electronic Frontiers Australia, which monitors online freedoms and rights, says the Government's plan is flawed.

"Although it may address some technical issues, what it leaves out is far more important," Electronic Frontiers Australia vice chair Colin Jacobs said.

"Exactly what will be blocked? Who will decide and why is it being attempted in the first place?"

Mr Jacobs says the ease with which users can circumvent the filtering raises questions about what it is actually trying to accomplish.

"What we're talking about is a filter that can only intercept accidental access to prohibited material," he said.

"Any motivated user will be able to get around it, it will be quite easy, so who is this being targeted at?

"If it's targeted at the people who traffic in illegal material, well, then clearly it's going to be worthless because they'll be able to get around it any time they want to.

"If it's teenagers the same is true unfortunately, and given the types of material that are going to be on the blacklist, younger children are unlikely to be affected one way or the other."

Transparency

Senator Conroy says the Government will take steps to ensure the filter is transparent and people know why material is being blocked.

This may include measures which allow people to appeal the decision to block a page and notifications to websites that they have been blocked.

The Government has been trialling the filter since late May and was due to report in July on the outcomes of the trial.

It has faced fierce criticism that it will strangle free speech on the internet, is open to potential government abuse and will ban sites that should not be coming under scrutiny.

In March, an alleged list of about 1,000 sites already banned by the Australian Communications and Media Authority (ACMA) was leaked online, revealing that harmless sites had also been marked as unacceptable.

Nine ISPs originally agreed to take part but iiNet pulled out of the trial in March, saying the filter would not work and was a dead parrot.

However, Optus joined the trial in April.

In May 2008, the Government said it would spend $125.8 million over four years on several measures to strengthen cyber safety, including the filter.

The Government maintains the filter is not designed to curtail freedom of speech.