The Stuff news outlet reported that earlier in the day, the suspect appeared in the High Court at Christchurch via a video link from a high-security wing in Auckland Prison where he had been staying.
Tarrant appeared before the court in relation to the mosque massacre for the first time on March 16, when he faced one murder charge. However, the police said on Thursday that the suspect would face 50 murder and 39 attempted murder charges.
The attack on mosques took place on March 15 and left 50 people killed and as many injured.
Brenton, who is an Austrian national and a resident of New Zealand, was captured by the police on the day of the massacre.
READ MORE: Austria's Kurz Confirms Link Between Christchurch Shooter and Right-Wing Group
The gunman is known to have livestreamed the shooting on social media and have published a manifesto filled with anti-Muslim statements prior to committing the attack.