Facebook has vowed to ban praise, support and representations of white nationalism and white separatism.

Axar.az reports citing Sky news that, in a blog post called Standing Against Hate, Facebook said the ban would come into force next week and would also apply to Instagram.

The move comes almost two weeks after a white nationalist killed 50 people in two mosques in the New Zealand city of Christchurch.

The terrorist, an Australian, live-streamed his attack on Facebook and the world's largest social media platform was among those criticised for being slow to take the footage down.

Facebook and other social media websites have also long been under pressure to do more about hate, fake news and abusive posts.

White supremacy was already under Facebook's rules about hateful content but white nationalist or separatist content had not been deemed by the site as racist.

The company said it had been reluctant to infringe on broader concepts of nationalism and separatism which it said are "an important part of people's identity". It gave the examples of American pride and Basque separatism.

"But over the past three months our conversations with members of civil society and academics who are experts in race relations around the world have confirmed that white nationalism and separatism cannot be meaningfully separated from white supremacy and organised hate groups.

"Going forward, while people will still be able to demonstrate pride in their ethnic heritage, we will not tolerate praise or support for white nationalism and separatism," it said.

New Zealand's prime minister Jacinda Ardern responded by saying material similar to that which reportedly inspired the Christchurch terrorist should have been banned long ago.

She added: "Having said that, I'm pleased to see that they are including it, and that they have taken that step, but I still think that there is a conversation to be had with the international community about whether or not enough has been done.

"There are lessons to be learnt here in Christchurch and we don't want anyone to have to learn those lesson over again."

Facebook also said it will connect people who search for white supremacy terms with an organisation called Life After Hate, which helps people leave hate groups.

Meanwhile, Kensington Palace said Prince William will visit New Zealand next month to honour the victims of the mosque attacks.

He will make the trip on behalf of the Queen and will meet survivors and others affected.

More details will be released closer to the time, the palace said.