The Australian man accused of killing 51 worshippers at two mosques in New Zealand in March pleaded not guilty to all charges in court in Christchurch on Friday.

Brenton Tarrant, who appeared by video link, entered his plea through his lawyers.

The High Court Justice Cameron Mander said the trial will commence on May 4 next year. Tarrant has been remanded in custody until Aug. 16 when a case review hearing is scheduled.

The self-proclaimed white supremacist has been charged with 51 counts of murder, 40 of attempted murder and engaging in a terrorist act over the March 15 atrocity in the South island city.

The 28-year-old Australian allegedly opened fire in the packed Al Noor mosque during Friday prayers and then traveled across town to continue the carnage in the suburban Linwood mosque.

The court heard that mental health assessments had found Tarrant was fit to stand trial for the worst massacre in modern New Zealand history.

About 80 survivors and relatives of those killed packed into the courthouse's public gallery for a glimpse of Tarrant.