Australia ordered internet providers on Monday to block eight websites that published content linked to the Christchurch mosque massacre - a first under new censorship rules.

After the alleged gunman, an Australian national, live-streamed the killing of 51 worshippers at two New Zealand mosques in March, Canberra has looked to expand its censorship powers.

The overseas websites were blacklisted because they "continue to provide access to the video of the Christchurch terrorist attacks or the manifesto of the alleged perpetrator," said Julie Inman Grant, Australia's eSafety commissioner.

Authorities refused to name the websites - which will be blocked for at least six months - saying it could bring them more traffic. Several other websites were asked to take down content and had complied, Inman Grant said.

"The remaining rogue websites need only to remove the illegal content to have the block against them lifted," she said.

One of the eight websites was a blog focusing on the so-called "Threat of Islam," according to an explanatory statement lodged with the Federal Register of Legislation.

The Communication Alliance - a telecommunications lobby group - said internet providers had already blocked all eight websites voluntarily before the order, but welcomed the legal clarity provided by the government decision.

In defense of the new censorship powers put into action by Australia's conservative government, Prime Minister Scott Morrison said last month, "That type of abhorrent material has no place in Australia."