A white supremacist who killed 51 people at two mosques in New Zealand will serve life in jail without parole - the first person in the country's history to receive the sentence. Australian Brenton Tarrant, 29, admitted to the murder of 51 people, attempted murder of another 40 people and one charge of terrorism. The judge called Tarrant's actions "inhuman", saying he "showed no mercy". The attack last March, which was livestreamed, shocked the world. Tarrant's sentencing also marks the first terrorism conviction in New Zealand's history. "Your crimes are so wicked that even if you are detained until you die, it will not exhaust the requirements of punishment," said Judge Cameron Mander in a Christchurch court on Thursday. On imposing a sentence of life without parole, Justice Mander said: "If not here, then when?" A sentence without parole means the offender will not be given the opportunity to leave prison after serving only a portion of their total sentence. Justice Mander said such life sentences without parole were reserved only for the "very worst murders". New Zealand does not have the death penalty as part of its justice system. New Zealand Prime Minister Jacinda Ardern, upon hearing of Tarrant's sentencing, said it meant he would have "no notoriety, no platform... and we have no cause to think about him, to see him or to hear from him again". "Today I hope is the last where we have any cause to hear or utter the name of the terrorist," she said. The shootings prompted New Zealand to pass stricter gun laws and buy back certain types of weapons from owners.