National leader calls Vladimir Putin a 'war criminal', wants NZ to help Ukraine anyway it can

National leader Christopher Luxon has labelled Russian President Vladimir Putin a war criminal for the atrocities carried out in Ukraine.

While Luxon supported the acts being investigated by the International Criminal Court, he told AM it was pretty obvious from the "incredibly atrocious images coming out of the war-stricken country that Putin was a war criminal".

Distressing reports of Ukrainian civilians being abused, murdered and buried in mass graves in Bucha, close to the capital Kyiv have come to light this week.

Luxon said he was just calling it as he saw it.

"We are seeing some pretty atrocious images, this is a war that's being covered 24/7... we are all seeing what's happening there. I get the point that we need to go through International Criminal Court, no doubt about it, understand that, but let's not sort of hide behind wishy-washy words - let's call it as we see it and that's yep, it looks like war crime."

Luxon also believed New Zealand should be supporting Ukraine in any way it could including supplying weapons.

New Zealand had supported in the intelligence and humanitarian space and it should be up for the conversation to supply lethal aid too, he said.

Luxon said he hadn't been aware until yesterday that Ukraine had asked for weapons and that Cabinet had decided against it. Now he knew the request was there, he would say yes, support them.

"From our point of view we should be backing our allies..."

Earlier this week Ardern would not go as far as calling Putin a war criminal, but said the evidence indicated Putin's regime was committing war crimes.

"Ultimately it is for the International Criminal Court to make that determination."

Ardern said she was not an ICC judge, so it was not her place to affix the "war criminal" label.