Donald Trump has angrily complained he is being blamed for the far-right terror attack in Christchurch, which has claimed the lives of 50 people.

"The Fake News Media is working overtime to blame me for the horrible attack in New Zealand. They will have to work very hard to prove that one. So Ridiculous!" Mr Trump tweeted on Monday morning.

It comes after the US president was criticised for directing followers on Twitter to Breitbart, a far-right website with a history of anti-Muslim rhetoric, in the hours after the shootings at two mosques in New Zealand last week.

He later extended his "warmest sympathy" and "best wishes" to the "people of New Zealand, but failed to label the shootings a terror attack or criticise the white supremacist ideology behind it - in stark contrast to his rapid response to Islamist terror attacks.

Mr Trump later denied there was a "rising threat" from white nationalism in the wake of the atrocity.

"I think it’s a small group of people that have very, very serious problems," he told reporters at the White House on Friday.

It came despite white supremacist killings in the US more than doubling last year, according to Southern Poverty Law Centre (SPLC), which monitors extremist violence. In a report last month, the organisation accused the president of pushing “noxious anti-immigrant and anti-Muslim ideas into the public consciousness”.

Some commentators have claimed Mr Trump's hostile policies and rhetoric about Muslims has contributed to an emboldening of white supremacism and Islamophobic views.

During his campaign for the presidency, Mr Trump called for a "total and complete shutdown" of Muslims entering the US and told supporters he would look at ways to "get rid of them" from the country.

The massacre on Friday has sparked renewed warnings about the growing threat of neo-Nazism, and followed deadly far right attacks in the the US, the UK and elsewhere in Europe in recent years.

The suspect charged over the Christchurch attack is believed to have links with violent racist groups in Europe and Asia. Brenton Tarrant is thought to have met with extreme right-wing organisations in Europe two years ago, according to security sources.

In a self-styled “manifesto” published online, the 28-year-old said he had been inspired by white supremacist terrorist Anders Breivik, who killed 77 people in Norway in 2011. He also referenced Dylann Roof, who shot dead nine black churchgoers in Charleston, South Carolina, in 2015 in a purported attempt to start a race war.