The accused Australian gunman behind the Christchurch terror attack will face 50 murder charges and 39 attempted murder charges.

The charges against Brenton Tarrant, 28, were announced by police on Thursday. He is due to appear at the High Court in Christchurch on Friday.

Previously, the accused had only been formally charged with a single count of murder following the March 15 attack that killed 50 and injured 50 more.

He appeared in District Court for this charge on March 16.

Despite labelling the shooting an act of terrorism, authorities had not said whether the former NSW resident would be the first person charged under New Zealand's anti-terror laws.

AAP

The country's terrorism legislation has in the past proved unwieldy and complex, and legal experts have said terror charges may just complicate the prosecution for no material difference in outcome if he is convicted.

"Other charges are still under consideration," police said on Thursday.

Friday's court appearance

The Australian man is being held in New Zealand's only maximum security prison, in Auckland, and has had no access to television, radio, newspapers or visitors.

He will appear at the High Court by video link on Friday, but is not required to enter pleas to the charges.

A note from the court this week said the appearance was likely to be brief and would "ascertain the defendant's position regarding legal representation" and other procedural matters.

The accused sacked a court-appointed lawyer after his first court appearance, raising fears he wanted to represent himself and attempt to use any trial as a propaganda platform.

Several national and international media outlets have made applications to film and record Friday's court proceedings. They were all denied by High Court Justice Cameron Mander.

Journalists will be able to attend and take notes.

SNPA

The attack prompted an outpouring of grief around the country and triggeed major changes to its gun laws.

Sixteen victims of the attack still remain in hospital this week, including a critically hurt four-year-old girl.

Additional reporting: AAP, AFP