PM: 'You won't hear me speak his name'

The man accused of gunning down 50 people at two New Zealand mosques has dismissed his lawyer and opted to represent himself at trial, prompting the Prime Minister to declare she will do everything in her power to deny him a platform for his views.

"I agree that it is absolutely something that we need to acknowledge, and do what we can to prevent the notoriety that this individual seeks," Jacinda Ardern told reporters today.

"He obviously had a range of reasons for committing this atrocious terrorist attack. Lifting his profile was one of them. And that's something that we can absolutely deny him."

Asked if she would like the trial to occur behind closed doors, Ardern demurred, saying that was not her decision to make.

"One thing I can assure you - you won't hear me speak his name," she said.

The gunman's desire for infamy was made clear by the fact that he left behind a convoluted 74-page manifesto before Friday's massacre and live-streamed footage of his attack on the Al Noor mosque.

The video prompted widespread revulsion and condemnation by lawmakers and members of the public. Facebook said it removed 1.5 million videos of the shootings during the first 24 hours after the massacre. But today, Ardern expressed frustration that the video remained available online, four days after the attack.

"We have been in contact with Facebook; they have given us updates on their efforts to have it removed, but as I say, it's our view that it cannot - should not - be distributed, available, able to be viewed," she said. "It is horrendous and while they've given us those assurances, ultimately the responsibility does sit with them."

Arden said she had received "some communication" from Facebook's chief operating officer Sheryl Sandberg on the issue. Ardern had also spoken with British Prime Minister Theresa May about the importance of a global effort to clamp down on the distribution of such material.

Lawyer Richard Peters, who was assigned to represent alleged gunman Brenton Harrison Tarrant at his initial court appearance on Saturday, told the New Zealand Herald that the 28-year-old Australian dismissed him that day.

A judge ordered Tarrant to return to New Zealand's High Court on April 5 for his next hearing on one count of murder, though he is expected to face additional charges. He is being held in isolation in a Christchurch jail.

"He seemed quite clear and lucid, whereas this may seem like very irrational behaviour," Peters told the newspaper. "He didn't appear to me to be facing any challenges or mental impairment, other than holding fairly extreme views."

Peters did not immediately return a call from The Associated Press.

He said a judge could order a lawyer to assist Tarrant at a trial, but that Tarrant would likely be unsuccessful in trying to use it as a platform to put forward any extremist views.

Under New Zealand law, a trial is "to determine innocence or guilt," Peters said. "The court is not going to be very sympathetic to him if he wants to use the trial to express his own views."

Peters said Tarrant didn't tell him why he wanted to represent himself.