Telstra, Optus and Vodafone have instituted temporary ISP-level blocks on websites hosting footage of last Friday’s Christchurch attacks.

Both Telstra and Vodafone released similar statements as pressure mounted for action to be taken against news organisations and platforms that enabled the attack to be broadcast live or replayed.

“We've started temporarily blocking a number of sites that are hosting footage of Friday’s terrorist attack in Christchurch,” Telstra said in a statement on Twitter.

“We understand this may inconvenience some legitimate users of these sites, but these are extreme circumstances and we feel this is the right thing to do.”

“Vodafone Australia has today started the process of temporarily blocking sites known to be actively hosting footage of Friday’s shootings in Christchurch,” a spokesperson said.

“We understand users trying to access these sites for legitimate purposes may be inconvenienced but we believe it’s the right thing to do in these extreme circumstances to help stop the sharing of this video.”

iTnews understands that Telstra and Vodafone’s similarly-timed decision and wording was not a result of a coordinated response, driven either by the telcos or by law enforcement or regulators.

Optus told iTnews at 9.40am that it would "only block websites when directed to by Australian law enforcement and Government agencies".

However, by 3pm it had changed its tune: "Reflecting on community expectations, Optus has blocked domains which are hosting video footage/sensitive materials relating to the recent Christchurch attack in New Zealand," a spokesperson said.

The site blocks coincided with a formal investigation launched by the Australian Communications and Media Authority (ACMA) into the extent to which Australian TV stations - and their online platforms - used the “content of the perpetrator-filmed, live streamed footage of the shootings”.

ACMA said that policing use of the offending video on websites is “currently beyond its regulatory remit” but said it would work with the Australian Press Council “as it reviews its members’ coverage of the attack.”

Social media platforms like Facebook are also facing questions over how they control the use and spread of live-streaming video.

NZ internet providers share blocking concerns

New Zealand’s three largest broadband providers - Vodafone NZ, Spark and 2degrees - all suspended access to websites hosting the offending video footage in the wake of the attack.

Together, they today urged Facebook, Twitter and Google, to come to the table with industry and government for an “urgent discussion” on how to restrict access to or remove offensive material hosted on their platforms.

The internet providers said they were “the ambulance at the bottom of the cliff, with blunt tools involving the blocking of sites after the fact.”

“The greatest challenge is how to prevent this sort of material being uploaded and shared on social media platforms and forums,” they said in a letter published today.

The three providers raised concerns with the use of website blocking as a means of accomplishing this outcome.

“We … accept it is impossible as internet service providers to prevent completely access to this material, but hopefully we have made it more difficult for this content to be viewed and shared,” they said.

“We [also] acknowledge that in some circumstances access to legitimate content may have been prevented, and that this raises questions about censorship. For that we apologise to our customers.

“This is all the more reason why an urgent and broader discussion is required.”

Updated 2.00pm: Added commentary from NZ internet providers

Updated 3.05pm: Updated to reflect change of position by Optus.