The soldier, whose name has been suppressed, admitted to attempted espionage, accessing a computer system for a dishonest purpose and knowingly possessing an objectionable publication.

The court martial at Linton Military Camp near Palmerston North heard the soldier gave military base maps and photographs to an undercover officer posing as an agent for the foreign nation.

During the investigation he was found to have copies of a livestreamed video of the March 2019 killing of 51 worshippers at two mosques in Christchurch by white supremacist Brenton Tarrant.

The soldier became a person of interest in the aftermath of the Christchurch attack as police cracked down on right-wing extremist groups, of which he was a member, the court heard.

While monitoring him, the New Zealand government became aware he had "made contact with a third party, indicating that he was a soldier who was wanting to defect", according to an agreed summary read out by the prosecution.

The military court has permanently suppressed the identity of the foreign nation.

It was the first spying conviction in New Zealand's history.

The soldier was arrested in December 2019, and had spent all but six days since then under what the New Zealand Defence Force called open arrest.

He was required to live on an army base in a military house, and was subject to a curfew.

The soldier was suspended on full pay, earning more than US$230,000 (NZ$400,000) since his arrest.

During that time he married his wife and had two children. His wife is expecting a third child.