WELLINGTON • New Zealand Prime Minister Jacinda Ardern yesterday welcomed Facebook's move to curb support for white nationalism on its platforms but said more needed to be done in the wake of the Christchurch mosque attacks.

The social media giant has unveiled tougher guidelines on hate speech for Facebook and Instagram, ruling that white nationalism and white separatism are both linked to organised hate groups and will be banned.

When making the announcement, the California-based company did not specifically reference the March 15 Christchurch atrocity that claimed 50 lives when a self-avowed white supremacist targeting Muslims opened fire in two mosques.

But Ms Ardern made it clear she believed it was a direct response to the criticism that has since been levelled at Facebook, which the accused gunman used to livestream the attack.

"Arguably these categories should always have fallen within (Facebook's) community guidelines on hate speech," she told reporters. "But it's positive that clarification has now been made in the wake of the attack here in Christchurch."

She added that "there's more work to do", and said New Zealand would play an active role in the debate.

"There are lessons to be learned here in Christchurch and we don't want anyone to have to learn those lessons over again," she said.

Ms Ardern said the goal was to limit harmful content "while preserving a free, open and secure Internet".

Noting that countries including Australia, Ireland and Germany were all wrestling with the issue of dealing with extremist material on social media, Ms Ardern said a global approach was needed.

"We can all promote good rules locally, but these platforms are global and I believe, therefore, that the solutions will need to be too," she said. "I think there would be a benefit for there being a globally coordinated response, that is what New Zealand will be looking for."

On Tuesday, Australia warned social media executives that they could be jailed for failing to quickly take down extremist material.

Social media platforms "can get an ad to you in half a second", Australia Prime Minister Scott Morrison told reporters.

"They should be able to pull down this sort of terrorist material and other types of very dangerous material in the same sort of time frame and apply their great capacities to the real challenges to keep Australians safe," he added.

AGENCE FRANCE-PRESSE