Money pledged toward weapons for Ukraine would be better spent on humanitarian relief the Green Party says.

The government is sending $7.5 million to the United Kingdom to procure weapons and ammunition as part of its latest suite of supports.

It is a marked shift in New Zealand's contribution to date and a decision the Prime Minister Jacinda Ardern said was not taken lightly.

"This sits squarely with New Zealand's values. Here we have a clear breach of the international rules-based order. We have a country's territorial sovereignty being challenged.

"We have a war [in] which everyone can see there is evidence of war crimes and impacts on civilians. This is New Zealand playing our part and it's a significant part."

New Zealand is sending a Hercules aircraft with 50 defence force personnel to Europe for two months to transport equipment and supplies distribution sites.

Cabinet also agreed to extend New Zealand's financial contribution by an extra $13 million, $7.5m of which will go towards weapons and ammunition.

Green Party defence spokesperson Golriz Ghahraman said while it was great some of the new funding was being spent on humanitarian relief, the government should commit the entire $13m to it.

READ MORE

• New Zealand to send Air Force Hercules to Europe to assist Ukraine military aid effort
• New Zealand dispatches 50 troops to Europe to assist with logistics of moving weapons into Ukraine
• Full-scale Russian offensive in eastern Ukraine looming
• Geoffrey Miller: Jacinda Ardern and Nanaia Mahuta struggle in Ukraine lethal aid debate

"That amount could make a huge difference if we had given it in humanitarian relief. It could save so many more lives and make so many more people safe."

Ghahraman said she believed New Zealand's contribution to weapons for Ukraine was driven by diplomatic relations and alignment with international partners.

"In terms of where New Zealand is best-placed to get engaged in this war, it isn't by providing weapons and being that kind of actor. It's less effective, we do it less well and we're contributing to something that we understand less of.

"What New Zealand and the entire international community has been called upon - to provide immediate humanitarian relief, and we've now somehow made a decision that we're giving more in military aid than humanitarian relief, so that's a bit disappointing."

National Party foreign affairs spokesperson Gerry Brownlee said he supports the latest measures announced for Ukraine.

"[The government has] clearly come to terms with the fact that they do need to supply arms and ammunition to people who are clearly trying to defend themselves, and a lot of those people trying to defend themselves are civilians."

He said the Green Party's call for the entire $13m to be spent on humanitarian relief was "complete nonsense".

"Of course we want humanitarian assistance to go to so many people who are displaced ... the fact is now they are under attack, massive attack, and we're seeing that every night on our television screens. I'd ask the question, who wouldn't want to help people in that circumstance?"

The new measures bring New Zealand's total contribution to Ukraine to $30m and 67 people deployed.

The Hercules will head to Europe on Wednesday.