New Zealand soldiers got high on prescription drugs while in Fiji on mission

Kiwi soldiers got high on prescription drugs on an active mission in Fiji last year.

Their commanding officers discovered the offence after noticing strange behaviour - including attacking a table with a machete and one of the soldiers "flipping out".

The four soldiers bought more than 100 pills from a local pharmacy in Suva, then took them on board HMNZS Canterbury while helping with the clean-up of Cyclone Winston in Fiji in 2016.

So many pills were bought that a senior military official was concerned they were planning to smuggle them back to New Zealand.

The details of the drug taking have come to light after documents were released under the Official Information Act to Fairfax.

The incident follows three Royal New Zealand Navy staff who were stood down after the alleged use of illegal substances while in Australia last year.

An internal investigation launched by the New Zealand Defence Force found that after the drugs were purchased without a prescription, and two of the soldiers had hidden them in a leather bible case which they then placed in a cyclone-damaged house.

Another of the soldiers stashed some pills in the light above their bed, while another hid pills in the rubble of a ruined church, Fairfax reported.

During the investigation more than 100 pills were seized, including Valium, tramadol, amitriptyline and Viagra.

Since then, four of the soldiers have been discharged from the armed services. One of the four was of a higher rank than the rest. A fifth was found not guilty at a summary trial last year.

After buying the drugs, the men returned to the ship where they each ingested different amounts of Valium, a prescription drug in New Zealand and Fiji, to get high.

When questioned by an investigator, one of the soldiers hid his phone from officials in an attempt to cover up the offending.

It is believed the phone held a picture of Valium crushed up next to a rolled up dollar bill, as noted in the documents released from the investigation.

Commander Simon Rooke said the soldier "stunk" of lying, Fairfax reported.

"I have spent 25 years watching and talking to sailors in various situations and consider I'm pretty good at smelling a lie, and he stunk of it."

Rooke was also concerned the men may have been trying to smuggle some of the drugs back to New Zealand - something the men denied, according to Fairfax.

Military expert Paul Buchanan said the fact a soldier of a higher rank took part in the offending was concerning.

"That might be someone as low ranking as a corporal, but that indicates at the lower end there were failings of leadership. That has got to be a serious worry to at least the part of the army these people were serving in," he said.

"It is very, very serious offending."

Buchanan said it would be concerning if the offending was reflective of a larger drug problem in the military.

"The NZDF has to address this seriously."

The NZDF wasn't available for comment, Fairfax reported.

Labour's Defence spokesman Phil Goff said last year that the two alleged substance-related incidents over a short period was "very concerning" and indicated a systemic problem.