More charges have been laid against the Australian man accused of the March 15 Christchurch terrorist attacks.

Key points: Carrying a number of high-powered weapons, Tarrant stormed two mosques during Friday prayers

Carrying a number of high-powered weapons, Tarrant stormed two mosques during Friday prayers The victims' families and survivors were told about the new charges at a meeting with police on Tuesday afternoon

The victims' families and survivors were told about the new charges at a meeting with police on Tuesday afternoon Tarrant is being held at a maximum security prison in Auckland

New Zealand police charged Brenton Harrison Tarrant with one count of engaging in a terrorist act. An additional murder charge and two additional attempted murder charges were also filed.

Tarrant is now facing 92 charges — 51 charges of murder, 40 of attempted murder, and one terrorism charge.

The victims' families and survivors were told about the new charges at a meeting with police on Tuesday afternoon.

"The charge will allege a terrorist act was carried out in Christchurch on 15 March 2019 and follows consultation between Police, Crown Law and the Christchurch Crown Solicitors Office," NZ police said in a statement.

Tarrant was arrested on March 15 for his involvement in the shooting deaths of 51 people at two mosques in Christchurch. He was initially charged with one count of murder.

He stormed the mosques during Friday prayers with a number of high-powered weapons and live-streamed the attack online, in what is alleged to be the single-worst terrorist attack carried out by an Australian.

New Zealand Prime Minister Jacinda Ardern said Tarrant had been in possession of a "category A" gun licence, obtained in 2017.

It allowed him to legally obtain the weapons in December 2017, and he was not on any watchlists prior to the attacks.

Ms Ardern said the 28-year-old Australian had based himself in the city of Dunedin prior to the attack.

Tarrant is being held at a maximum security prison in Auckland and has appeared at the Christchurch High Court via video link.

At a March 16 court appearance, Tarrant did not apply for bail or for the suppression of his name, and he made a white power gesture as he was brought into the court.

During a subsequent court appearance on April 5 the presiding judge, Justice Cameron Mander, ordered a mental health assessment to determine Tarrant's fitness to enter a plea.

Justice Mander said this was an entirely normal undertaking.

Tarrant is being represented by Auckland-based barristers Shane Tait and Jonathan Hudson.

He is due back in court in June.