New Zealand Prime Minister Jacinda Ardern says she wants tech companies to make more progress on algorithms that can drive social media users to radicalisation.
Along with France, New Zealand is leading a push to rid the world of extremist and terrorist content online - known as the Christchurch Call.
The initiative follows the horrific terrorist attack that took place in New Zealand in 2019, which was livestreamed and stored online.
On Saturday morning (AEST), Ms Ardern and co-chair Emmanuel Macron hosted world leaders, tech company executives and affected communities - including Kiwi Muslim leaders - in a virtual Christchurch Call summit.
Attendees of the summit included US secretary of state Anthony Blinken, Canadian Prime Minister Justin Trudeau, and other heads of government.
Ms Ardern said the agreement, which brings together countries and tech companies to try and de-radicalise online spaces, had "such momentum".
"We will not ... prevent future atrocities such as what we experienced here on March 15 unless we work together," she said.
The group has devised a new work program for the next year - and among its goals is tweaking how people are served up online content by tech companies.
A key finding of the Royal Commission into the Christchurch Mosque attacks was that the terrorist responsible - Australian man Brenton Tarrant - was radicalised on YouTube and other online spaces while viewing white supremacist material.
YouTube is programmed, using algorithms, to link users to similar videos, which can lead to vulnerable people being saturated in extremist content.
After her country's experience, Ms Ardern wants to see this change - and believes that it is happening.
"That is probably the biggest focus for the Call community over the next year," she said.
"Let's have that conversation around the ethical use of algorithms, and how they can use be used in a positive way and for positive interventions.
When we look at the environment in which the terrorist for March 15 was radicalized, even in that period in those two years there has been significant change by many of the platforms.
"Algorithms are where many of us are looking to."
YouTube chief executive Susan Wojcicki said on Twitter her company was continuing "to strengthen our policies, improve transparency, and restrict borderline content".
After holding out on membership for two years, the United States joined up as a supporter of the Call this week.
China and Russia are not members, which challenges the initiative's effectiveness.
The Christchurch Call has also developed a protocol which can intervene to stop the livestreaming of similar attacks.
This has occurred twice, during a 2019 shooting in Halle, Germany and a 2020 attack in Glendale, Arizona.
Australian Associated Press