The Green Party has criticised Air New Zealand following revelations it has been helping the Saudi Arabian military - despite the Middle Eastern nation's role in the humanitarian crisis in Yemen.

1 News reported that the national carrier's business unit, Gas Turbines, which specialises in servicing military marine engines and turbines, has been supporting the Saudi Navy.

In a statement, Air New Zealand said the business unit carried out work on Royal Saudi Navy vessels through a third party contract.

"The business … occasionally contracts to carry out ad hoc overflow work from third party repair facilities. It is through a third party contract that work has recently been carried out on two engines and one power turbine module from vessels belonging to the Royal Saudi Navy.

"The Gas Turbines business has not contracted directly with the Royal Saudi Navy and will not be carrying out any further work of this nature."

It said the business unit was reviewing its contracting processes to ensure it had "improved oversight" of future work assigned through third party arrangements.

Green Party human rights spokeswoman Golriz Ghahraman said her thoughts were with the Yemeni community who continued to suffer one of the worst atrocities in human history, including mass starvation and violence causing hundreds of thousands of civilian deaths, leaving millions displaced

New Zealanders would be heartbroken to learn of our national carrier's possible links to the Yemeni crisis.

The airline's move to cease all support of the Saudi military after the matter came to light was welcomed, she said.

"However, we as a nation have an absolute legal and moral duty to investigate, and hold to account anyone in Air New Zealand's leadership," she said.

"If those in Air New Zealand HQ were not aware of what was going on, it needs to be established how that was allowed to happen."

Amnesty International campaign director Lisa Woods told 1 News she would've expected the airline to have carried out due diligence about the human rights risks and in doing so consider what impact their services would have.

"We would be appalled if there was any company here (in New Zealand) that through their activities were contributing to human rights violations and having an adverse impact on human rights."

Grant Robertson, Air New Zealand's shareholding minister, was not aware the airline had been supporting the Saudi military until contacted about the story.

The Government owns 52 per cent of the national airline.