The United States is not endorsing a global pledge to step up efforts to keep internet platforms from being used to spread hate, organise extremist groups and broadcast attacks, citing respect for "freedom of expression and freedom of the press".

Key points: Australia, India and EU nations backed the pledge, as did major US tech giants

Australia, India and EU nations backed the pledge, as did major US tech giants The non-binding initiative lets countries and companies decide how to apply guidelines

The non-binding initiative lets countries and companies decide how to apply guidelines The US said it was "not currently in a position to join the endorsement"

The Trump administration snubbed a meeting of world leaders and tech giants organised by New Zealand Prime Minister Jacinda Ardern in Paris, where the new set of guidelines known as the "Christchurch Call" were discussed.

French President Emmanuel Macron hosted Ms Ardern, British Prime Minister Theresa May, Canada's Justin Trudeau and other leaders on Wednesday to support the New Zealand initiative, named for the city where a gunman attacked two mosques on March 15 and broadcast his killings live on Facebook.

Signatories would "encourage media outlets to apply ethical standards when depicting terrorist events online, to avoid amplifying terrorist and violent extremist content," although the initiative is non-binding, light on details and leaves countries and companies to decide how to apply guidelines.

"Fundamentally it ultimately commits us all to build a more humane internet, which cannot be misused by terrorists for their hateful purposes," Ms Ardern said.

Countries including Australia, Germany, Japan, the Netherlands, Spain, India and Sweden said they backed it, as did US tech giants Microsoft, Alphabet's Google and its video platform YouTube, and Amazon.

But the White House said in a statement the US was "not currently in a position to join the endorsement," although it added: "we continue to support the overall goals reflected in the call".

Mr Macron put a positive spin on the White House response.

"We'll do everything we can so that there is a more concrete and formal commitment, but I consider … the fact that the US administration said it shared the objectives and the common will as a positive element," he said.

The Christchurch massacre has reignited the debate on whose responsibility it is to tackle online extremism. ( ABC News: Graphic/Jarrod Fankhauser )

Facebook to block some livestreaming

Meanwhile, Facebook announced steps to temporarily block users who break its rules from broadcasting live video, in the wake of an international outcry over the Christchurch attack that left 51 people dead.

Facebook said in a statement it was introducing a "one-strike" policy for use of Facebook Live, a service which lets users broadcast live video. Those who broke the company's most serious rules anywhere on its site would have their access to make live broadcasts temporarily restricted.

The company did not specify which offences would result in such a ban or how long suspensions would last, but a spokeswoman said it would not have been possible for the Christchurch shooter to use Facebook Live on his account under the new rules.

Facebook has come under intense scrutiny in recent years over hate speech, privacy lapses and its dominant market position in social media. The company is trying to address those concerns while averting more strenuous action from regulators.

Ms Ardern called the changes "a good first step to restrict the application being used as a tool for terrorists, and shows the Christchurch Call is being acted on".

The company also said it would fund research at three universities on techniques to detect manipulated media, which its systems struggled to spot in the aftermath of the attack.

Ms Ardern said the research was welcome and that Facebook had been slow to remove edited and manipulated videos of the mosque shootings, resulting in many people, including herself, seeing video of the killings played in their news feeds.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 11 minutes 53 seconds 11 m Ranking Digital Rights director Rebecca MacKinnon says Facebook's new live-streaming guidelines are a step in the right direction.

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