WELLINGTON — A senior New Zealand government minister was assaulted in an early-morning street attack Thursday that left him with a black eye and shook up Wellington’s normally laid-back political atmosphere.

Green Party co-leader James Shaw was walking to the parliament building known as the Beehive when a man punched him in the face in what his office described as an unprovoked attack.

While Shaw’s office played down any political aspect to the assault, Trade Minister David Parker told reporters the attacker "was said to be shouting things out about the United Nations".

Shaw, who is Climate Change Minister and whose party is part of the ruling centre-left coalition, was not seriously injured.

His office said two members of the public helped him and he continued to parliament, attending a meeting before going to hospital for a precautionary check-up.

He suffered a black eye, telling stuff.co.nz "it looks worse than it is".

Police said a 47-year-old man was arrested and would appear in court on Friday charged with injuring with intent.

Political violence is practically unheard of in New Zealand, a nation of about 4.5 million where most government ministers do not have a regular security detail.

Prime Minister Jacinda Ardern said that "in New Zealand, you just don’t expect these things to happen".

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

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

Wellington mayor Justin Lester said it was "a sad day for democracy".

"This is outrageous behaviour and if undertaken by a Wellingtonian, shameful," he tweeted.

"Elected representatives of all hues show courage to represent New Zealanders and we are lucky to have unparalleled access to them."

There was condemnation from across the political spectrum, with the leader of the conservative National Party Simon Bridges tweeting: "Violence is never OK."

Ardern said Shaw had told her he was doing fine" and she had told him to take whatever time off he needed to recover. — AFP