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 on Friday entered not guilty pleas to 51 charges of murder, 40 charges of attempted murder and one terrorism charge 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.

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

Wearing a gray sweat shirt, 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 scheduled a six-week trial beginning next May.