Britain's Prime Minister Boris Johnson walks down the street near United Nations headquarters in New York, Monday, Sept. 23, 2019. (AP Photo/Seth Wenig)

The leaders of New Zealand and France are backing a watchdog organization aimed at keeping internet platforms from being used by extremists—and preparing speedy responses to future attacks.

New Zealand Prime Minister Jacinda Ardern said Monday the Global Forum to Counter Terrorism, which was established in 2017 by Facebook, Microsoft, Twitter and YouTube after with internet links, is being turned into an independent organization.

The new organization is limited to companies operating and services and will be led by an executive director selected by its governing industry-linked Operating Board, Ardern said. An Independent Advisory Committee with a majority of members from and a minority from government and inter-governmental organizations will guide the Operating Board.

Ardern said establishing an independent organization marked "a real sea change to respond to the serious and difficult issue" of extremists who have recruited supporters and streamed attacks online.

The killings of 51 people at two mosques in Christchurch, New Zealand, on March 15 were broadcast live on Facebook, drawing outrage and fueling debate on how to better regulate social media.

Facebook Chief Operating Officer Sheryl Sandberg, the forum's current chair who joined Ardern at Monday's news conference, said "we've shared more than 200,000 digital fingerprints with our partners, because when terrorists try to use one , they try to use all platforms.

"And when one of us find them, we can take them down off multiple platforms," she said.

At a gathering in Paris in May, Ardern, French President Emmanuel Macron and others signed the "Christchurch Call," committing to act against terrorist and extremist content online.

British Prime Minister Boris Johnson, whose country is among almost 20 nations backing the "Christchurch Call," said at a U.N. meeting before the news conference that the internet must not become "a place to watch mass murder unfold."

He said scientists are working on technology to stop violent attacks from being broadcast live on the internet. The British government says it'll fund data-science experts to work on an algorithm to improve the detection of violent and harmful videos.

Ardern said more countries, organizations and online companies have signed on since May, including Google and Amazon.

The U.S. hasn't joined, citing , and tech firms are struggling with the sheer volume of content.

Ardern said the independent forum's goals include improving the capacity of technology companies to prevent and respond to abuse of their platforms by terrorists and violent extremists, and to fund research on their online operations.

"We're trying to create a civil defense-style mechanism," Ardern said. "The same way we respond to natural emergencies like fires and floods, we need to be prepared and ready to respond to a crisis like the one we experienced."

Sandberg said the fastest-growing message platforms are encrypted but people using them often use other platforms that are not, allowing them to be removed from both.

"We can't stop because we're going to have to stay one step ahead, learn from our mistakes, and continue to do all we can over the long-term," Sandberg said.