One of New Zealand’s largest telecommunications providers, Spark, has banned the far-right site 8chan after the country’s chief censor offered his backing for any internet service provider who did so in the wake of the El Paso mass shooting.

Censor David Shanks applauded Spark’s “brave and meaningful” decision, describing the message board as “the white supremacist killer’s platform of choice”.

“These are extraordinary circumstances, and platforms that promote terrorist atrocities should not be tolerated on the internet, or anywhere else. Spark is making the right call here.” he said.

In announcing its decision, Spark said the platform was guilty of “repeated transgressions” and hosted “disturbing material”.

8chan – on which the El Paso suspect reportedly published his screed – has been temporarily forced offline while it looks for another host. Spark said that if the website became active again its customers in New Zealand would not be able to access it.

The El Paso document included expressions of support for the Christchurch gunman, whose livestreamed attack on worshippers in New Zealand in March left 51 people dead.

Spark’s move apparently came after Shanks said he would support any ISP that decided to ban 8chan. It said in a statement: “We’ve taken a consistent view that the appropriate agencies of government should put in place a robust policy framework to address the important issues surrounding such material being distributed online and freely available.

“As an internet service provider, we don’t make these decisions lightly and want to work with Government, the wider industry and civil society organisations to make the internet a better place for New Zealanders.”

Spark confirmed 8Chan was the only website it will block.

Shanks said he was aware that ISPs “do not want to be in the business of making judgments around the content of sites”.

“This is a unique set of circumstances, and relying on ISPs to make these calls is not a solution for the mid or long term. I agree with calls for a transparent, robust and sensible regulatory response. Discussions have already started on what this might look like here in NZ. Ultimately this is a global, internet problem.”

Following the mosque attacks in March, prime minister Jacinda Ardern has led a global effort to pressure internet providers and social media companies to eliminate terrorist and violent content online.

Known as the “Christchurch call”, Ardern said no one had a right to livestream mass murder. “We want to maintain the principles of a free, open and secure internet, but this isn’t about freedom of expression, this is about preventing violent extremism and terrorism online. I don’t think anyone would argue that the terrorist on the 15th of March had a right to livestream the murder of 50 people,” she said.

“We all need to act, and that includes social media providers taking more responsibility for the content that is on their platforms … it’s critical that technology platforms like Facebook are not perverted as a tool for terrorism, and instead become part of a global solution to countering extremism.”

According to geopolitical and strategic risk expert Paul Buchanan, users of 8chan commented on the Christchurch live feed, urging the killer on and applauding his efforts.

“8chan has become a hate fest and incites violence. I was monitoring 8chan as he was killing people in the mosque. They were cheering for him, they were saying that he should shoot people twice. It was horrifying,” said Buchanan.

“if you can read English, no matter where you are in the world, you can go to 8chan and have your white supremacist extremist views confirmed … how to make bombs, how to avoid surveillance. It’s full-on insurgent and guerrilla preparation.”

Following the Christchurch attack, Australian internet providers temporarily blocked access to sites hosting the shooter’s video of the massacre, including 8chan and 4chan.

However following the El Paso shooting, Australia’s version of the chief censor said websites carrying the manifesto did not reach the benchmark for censorship.

“When issuing such a direction, the esafety commissioner assesses whether the crisis event involves terrorist or extreme violent material being disseminated online in a manner likely to cause significant harm to the Australian community,” a spokesperson for Australia’s esafety commissioner told the Guardian.

“While the attack in El Paso was a heinous act of terror, in exercising our discretion we have determined the manifesto does not reach this threshold.”

Additional reporting by Josh Taylor