Prime Minister Jacinda Ardern says she will raise radicalisation directly with YouTube’s leadership following the Royal Commission of Inquiry’s report into March 15.

The terrorist told the Commission that YouTube was his main source of both inspiration and information on how to carry out the terror attack, which saw 51 worshippers murdered in two mosques.

The Commission itself agreed that this YouTube use was more substantive that his use of forums such as 4chan or 8chan, where he posted his manifesto in the minutes before the attack.

“The individual claimed that he was not a frequent commenter on extreme right-wing sites and that YouTube was, for him, a far more significant source of information and inspiration,” the report reads.

“Although he did frequent extreme right-wing discussion boards such as those on 4chan and 8chan, the evidence we have seen is indicative of more substantial use of YouTube and is therefore consistent with what he told us.”

In another part of the report it says it is plausible that the terrorist’s online activity contributed to the attack.

“He also visited other sites and discussion boards where there was discussion promoting extreme right-wing and ethno-nationalist views similar to his own and sometimes supporting violence. He also spent much time accessing broadly similar material on YouTube.

Former Google employee Tristan Harris told Stuff at the Christchurch Call meeting in 2019 that the company amplified more extreme content in order to push up user engagement.

"A teen girl will watch a dieting video and it will recommend an anorexia video because that is more extreme,” Harris said.

YouTube has pushed back against this characterisation of their recommendation engine in the past, with product chief Neal Mohan telling the New York Times that it did not take into account whether a video was more or less extreme.

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"It is not the case that 'extreme' content drives a higher version of engagement or watch time than content of other types," Mohan told The New York Times.

“His exposure to such content may have contributed to his actions on 15 March 2019 - indeed, it is plausible to conclude that it did,” the report reads.

A YouTube spokesperson said the company had not yet reviewed the report, but was committed to removing violent extremism and hate speech from its platform.

“We look forward to reviewing the report in detail and continue our work together with the Prime Minister, as well as governments, industry partners, and communities around the world to combat the spread of violent extremism online.”

YouTube has been accused in the past of encourage radicalisation or “red-pilling” with the videos it automatically suggests people watch, suggesting more and more “extreme” content in order to keep people engaged.

YouTube is the most popular website or station in New Zealand, according to a survey from NZ On Air.

Ardern noted the finding in her speech following the report and said she would raise it directly with YouTube, which is owned by Google.

“What particularly stood out was the statement that the terrorist claimed that he was ‘not a frequent commenter on extreme right-wing sites and that YouTube was, for him, a more significant source of information and inspiration.’ This is a point I plan to make directly to the leadership of YouTube,” Ardern said.

She said the work the Government was doing on social media as part of the Christchurch Call was not finished.

The Commission itself addressed this ongoing debate concerning YouTube, noting the company had made changes to its recommendation system, but that far right content was prevalent on the platform.

“There has been much debate about the way YouTube’s recommendation system works. One theory is that this system drove users to ever more extreme material into what is sometimes said to be a ‘rabbit-hole’. An alternative theory is that the way in which YouTube operates facilitates and has monetised the production of videos that attract viewers and the widespread availability of videos supporting far right ideas reflects the demand for such videos,” the report reads.

“What is clear, however, is that videos supporting far right ideas have been very common on YouTube. YouTube has made changes in response to these criticisms, in particular to their recommendation system, so it is less likely to continue recommending increasingly extreme content and has also made it more difficult to access extreme content.”