An internet protest group has launched an attack on Government websites in a protest against the proposed internet filter and censorship of some pornography.

The attack, dubbed Operation Titstorm by the group known as Anonymous, brought down a number of Government websites this morning, with the Parliament House site remaining offline well into the afternoon.

Anonymous claimed the attack was to highlight moves by the Government to ban the import of films featuring female ejaculation (which was classified as urination) as well as films featuring small-breasted women, over fears such films were simulating child pornography.

"More importantly, Anonymous does not approve of the steps already undertaken by the Australian Government to control what their populous [sic] sees," the statement said

"Claiming to be cracking down on 'simulated child pornography,' many depictions of women with small breasts in pornography have been banned," the group said in a statement.

"Officials cannot claim that they believe the models in these movies are in fact underage, as the production the titles that have been affected are heavily regulated to ensure the age of the models.

"Instead they are relying on earlier ambiguous wording that allows pornography featuring models that 'appear to be' under 18 years of age to be treated in the same manner as actual child pornography."

But lobby groups campaigning against internet censorship in Australia have condemned the attacks as "harmful".

Stop Internet Censorship co-founder Nicholas Perkins says any illegal action to protest censorship must be condemned.

"By attempting to bring down or deface government websites, a minority of internet users have brought negative attention to what is a very important issue for Australians," he said in a statement.

In a emailed reply to ABC News Online, an anonymous spokesperson for the group said the protest succeeded in raising awareness about internet censorship.

'Not afraid to act'

"The goal of today's attacks was to show the Australian Government that we are not afraid to act, and to raise awareness of the issue of internet censorship and our group's dedication to fighting it," the email said.

"Myself and the other protesters are quite satisfied with the results of our initial attacks.

The spokesperson also said while they understood concerns the group was doing more harm than good, they would continue to step up attacks on the Government.

"In terms of our response to claims that our attacks did more harm than good... this is a legitimate concern," the spokesperson said.

"These people should know that our recent attacks were simply the first of many planned protests.

"We plan to employ a variety of protesting methods in the future, including many quite different from those used today. Anonymous has quite a number of tricks up its collective sleeve."

Mr Perkins said Anonymous should instead focus on educating the public about the ineffectiveness of the proposed internet filter.

"Educating families, friends and the local community about that the filter will not work, does not target child pornographers or paedophiles, and could result in parents believing that their children are safe when they are not, is more important," he said.

"Parents need to be aware that any attempt to filter the internet by internet service providers will never work as well as filtering technologies that can be used within the home."'

A spokeswoman for the Attorney-General's Department said the Government was aware of the attacks and had briefed agencies identified as targets.

She said the Australian Parliament House website was down "due to a distributed denial of service attack by individuals belonging to the 'Anonymous' group".

"Australian Government agencies identified as potential targets by 'Anonymous' were briefed in advance and were provided with suggested mitigation strategies," the release said.

"The Department of Defence Cyber Security Operations Centre continues to monitor the situation."