The man accused of killing 51 people at two Christchurch mosques has pleaded not guilty to all the charges that have been filed against him.

Brenton Tarrant Friday entered not guilty pleas to 51 charges of murder, 40 charges of attempted murder and one terrorism charge Friday at the Christchurch High Court in relation to the March 15 massacre.

The 28-year-old Australian appeared via video link from a small room at the maximum security prison in Auckland where he's being held.

The courtroom was filled with 80 survivors and family members, while about another 60 watched the proceedings on video in an overflow room.

Four cultural advisers and other staff were assigned to help the victims and family members understand what was going on in court and the next steps in the case.

Tarrant's lawyer, Shane Tait, entered the pleas on Tarrant's behalf.

Brenton Tarrant, seen here in the Christchurch District Court March 16, has pleaded not guilty to all 92 charges against him in connection to the shootings at two mosques. (Mark Mitchell/Pool/The Associated Press)

Wearing a grey sweatshirt, Tarrant smirked as his lawyer entered the pleas but otherwise showed little emotion. His link had been muted, and he didn't attempt to speak.

Judge Cameron Mander said two mental-health assessments of Tarrant had been completed, and there were no issues in relation to the accused's ability to enter pleas and stand trial. Such mental-health assessments are standard procedure in murder cases.

The judge did not allow cameras or video in the courtroom. He scheduled a six-week trial beginning in May 4, 2020.

In an attack broadcast live on Facebook, a gunman armed with semi-automatic weapons targeted Muslims attending Friday prayers in Christchurch, in New Zealand's worst peacetime mass shooting.

New Zealand's Prime Minister Jacinda Ardern has vowed never to say the accused man's name.

Last month she helped lead a global pledge named the Christchurch Call, aimed at boosting efforts to keep internet platforms from being used to spread hate, organize extremist groups and broadcast attacks.