WELLINGTON, March 26 (Xinhua) -- The man accused of the Christchurch mosque attacks admitted on Thursday charges of murder, attempted murder and terrorism in a surprise court hearing.

Brenton Tarrant, 29, appeared via video-link in the Christchurch High Court on the first day of the national lockdown to prevent the spread of COVID-19.

He admitted 51 charges of murder, 40 charges of attempted murder and a charge of engaging in a terrorist act in a closed court hearing, local media reported.

Fifty-one people died in the Christchurch mass shootings on March 15, 2019, the darkest day on New Zealand's history.

"The guilty plea today will provide some relief to the many people whose lives were shattered by what happened on March 15," Prime Minister Jacinda Ardern said in a statement after the court hearing.

"These guilty pleas and conviction bring accountability for what happened and also save the families who lost loved ones, those who were injured, and other witnesses, the ordeal of a trial," Ardern said.

The accused pleaded not guilty to all the charges during previous hearings.

Tarrant, imprisoned at an Auckland Prison, was silent and emotionless throughout the court hearing, local media reported.