Britain's Home Secretary (Interior Minister) Sajid Javid has said social media companies must take action to stop violent extremism on their channels after Friday's massacre by an Australian white supremacist at two mosques in New Zealand.

The terrorist, a 28-year-old man called Brenton Tarrant, broadcast live footage on Facebook of the deadly attack on one mosque in the South Island city of Christchurch, mirroring the carnage played out in video games. Earlier he published a "manifesto" on Twitter in which he espoused anti-immigrant and Islamophobic ideology, and featured tropes familiar to white supremacist and alt-right movements.

The attack on two mosques in Christchurch has killed at least 49 people and injured more than 20 others. Tarrant identified himself online before live-streaming himself gunning down his victims.

The vile terrorist was inspired by Anders Breivik -- the Norwegian far-right mass murder who committed the 2011 Norway attacks where he killed 77 people -- and called for the deaths of German Chancellor Angela Merkel, Turkish leader Recep Erdogan and London Mayor Sadiq Khan in his "manifesto".

Facebook, Twitter and YouTube announced they would take down content involving the massacre which was posted online.

"You really need to do more @YouTube @Google @facebook @Twitter to stop violent extremism being promoted on your platforms," British Interior Minister Javid wrote on Twitter. "Take some ownership. Enough is enough."

Meanwhile, London Mayor Khan, a Muslim who was mentioned in the terrorist’s hate manifesto, condemned the terrorist attack against Muslims announced that police patrols in the British capital around local mosques would be increased.

"When the flames of hatred are fanned, when people are demonised because of their faith, when we play on people's fears rather than addressing them, the consequences are deadly, as we have seen so sadly today," Khan tweeted.

"In response to the horrific attack in New Zealand, I am in constant contact with @metpoliceuk who are stepping up reassurance patrols around mosques & increasing engagement with communities of all faiths," he continued.

Responding to Tarrant's rambling 73-page document called "The Great Replacement", Nick Lowles, of Britain's anti-extremism group Hope Not Hate, said: "The bloody terrorist attack in Christchurch was carried out by a far-right activist who has published a manifesto explaining why he did it.

"The terrorist's manifesto uses the stock phrases of the alt-right to justify murder, talking of 'white genocide' and citing spurious statistics about birth rates to explain away the savagery they have inflicted on people simply engaged in practising their faith.

"In so many places around the world, this violent ideology destroys lives and rips loved ones apart."  

While most of the mainstream Western media has refused to call the deadly incident a terrorist attack, New Zealand's Prime Minister Jacinda Ardem described it as an act of terrorism. 

"It is clear that this can now only be described as a terrorist attack,” Ardern said.

"What has happened in Christchurch is an extraordinary act of unprecedented violence. It has no place in New Zealand. Many of those affected will be members of our migrant communities – New Zealand is their home – they are us," she continued on Twitter.Source: presstv.com