Image copyright Hagen Hopkins Image caption Lawmakers of all political stripes expressed shock and concern over the incident.

New Zealand's climate change minister has been assaulted in the street while on his way to Parliament House.

Green Party co-leader James Shaw was punched in the face early on Thursday in Wellington, but not seriously injured.

PM Jacinda Ardern said: "In New Zealand, you just don't expect these things to happen."

It is proud of its culture of political openness, and this has raised questions about the accessibility of lawmakers.

"We have an environment in New Zealand where politicians are accessible, and that's something we should feel proud of," Ms Ardern told reporters.

"We are after all, here to serve people. But today's events really show we cannot take that for granted."

A 47-year-old man was arrested and will appear in court on Friday, police said.

A Green party spokesperson described the attack as unprovoked and said Mr Shaw, who suffered a black eye, went to the hospital for a precautionary check-up.

It is still unclear if the attack on Mr Shaw was politically motivated, but Trade Minister David Parker told local media the attacker "was shouting things out about the United Nations".

Lawmakers of all political stripes expressed shock and concern over the incident.