Conroy said the mandatory filter would not be imposed until completion of the review, which could take up to a year.

Friday's move buys the government a reprieve in protests and neutralises what would have been a potentially contentious topic as it prepares to call an election in the coming weeks.

Voluntary block

While the review is under way, three of Australia's largest internet service providers, Telstra, Optus and Primus, agreed to voluntarily block a government-compiled list of online child pornography material.

Conroy said he welcomed "the socially responsible approach taken by some of Australia's largest ISPs" - accounting for about 70 per cent of internet users - to voluntarily block the webpages, which he described as featuring "abhorrent" content.

In video


Al Jazeera's Azhar Sukri reports on Australia's debate over plans to filter the internet

The government's plan to block access to sites featuring material such as rape, drug use, bestiality and child sex drew criticism from firms such as Google, Yahoo! and Microsoft.

Angry user groups launched an online campaign accusing the government of censorship, while cyber-activists succeeded in jamming key government websites in a concerted campaign of protest hacking.

User advocates, the pornography industry and others have likened the proposed system to official firewalls operating in countries such as China and Iran.

But Conroy remained adamant that the filter proposal did not constitute censorship.

"I don't think any Australian actually tries to describe blocking child pornography or bestiality or pro-rape websites as censorship," he said.