A manifesto believed to have been written by the alleged Christchurch gunman has been officially classified as objectional and banned, the Office of Film & Literature Classification has confirmed.

Chief censor David Shanks confirmed the move on Saturday, urging anyone who had copies of it to destroy them.

It is now an offence, with Shanks describing the document as "a crude booklet that promotes murder and terrorism".

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A glowing editorial in the New York Times last night heaped praise on the way Prime Minister Jacinda Ardern has handled the fallout from the shocking events of last week in Christchurch.

In the wake of last Friday's terror attack on two mosques which killed 50 people, the actions of Ardern in swiftly moving to ban semi-automatic guns as well as her sympathetic response to the Muslim community has garnered worldwide attention.

The Times editorial entitled 'America Deserves a Leader as Good as Jacinda Ardern' said "the world should learn from the way Jacinda Ardern, New Zealand's prime minister, has responded to the horror".

In particular, Ardern's handling of the issues around gun control have struck a chord with the newspaper's editorial board.

"Ardern listened to her constituents' outrage and declared that within days her government would introduce new controls on the military-style weapons that the Christchurch shooter and many of the mass killers in the United States have used on their rampages," the editorial said. "And she delivered ... 'It's about all of us,' she said, 'it's in the national interest and it's about safety'."

The original photo: Prime Minister Jacinda Ardern hugs a mosque-goer at the Kilbirnie Mosque on Monday. Photo / Getty

The editorial also praised Ardern for the measured response to social media concerns after the video of the accused gunman's rampage appeared live on Facebook and other platforms.

"Earlier in the week, she told Parliament that social media sites must address the ease with which the internet can be used to spew hate and images of violence. 'We cannot simply sit back and accept that these platforms just exist and that what is said on them is not the responsibility of the place where they are published,' she said. 'It cannot be a case of all profit, no responsibility'.

"She made clear that she believed that those social media platforms, like gun manufacturers and dealers, bore some responsibility for the carnage visited on Christchurch and so many communities in recent years."

The issue of gun control - and the different ways the US and New Zealand approach the debate - also resonated.