A man has been charged with injuring with intent to injure after Green Party co-leader James Shaw was attacked on the street this morning.

Photo: RNZ / Rebekah Parsons-King

Politicians from all sides of the political spectrum have expressed shock at the unprovoked attack on the Climate Change Minister as he walked to work.

Mr Shaw suffered a black eye, bloody nose and lacerations to his face in the assault on Glenmore Street in Kelburn about 7.50am.

Two members of the public came to Mr Shaw's aid and called emergency services.

RNZ understands the man jumped out of a van and was shouting political comments aimed at Mr Shaw personally.

Police said a 47-year-old man has been arrested in relation to an assault on Glenmore Street this morning.

He has now been charged with injuring with intent to injure and is due to appear in Wellington District Court tomorrow.

Mr Shaw has given police a detailed statement, and they are asking for any witnesses to come forward.

Do you know more? Email us at iwitness@radionz.co.nz

Paramedics checked him out on scene and gave him the all-clear.

Mr Shaw then went to work and attended an environment cabinet committee meeting before heading to hospital for a precautionary check-up.

His visibly-shaken Green Party co-leader Marama Davidson told media this afternoon that the attacker seemed to know who Mr Shaw was, calling out his name.

"He's shaken. This was an individual who attacked him this morning and this is a big deal. And we're all shaken. But the messages of support are overwhelming and we are focused on supporting James at this time."

Ms Davidson said she hoped the incident did not result in politicians requiring heightened security.

"It would be a shame to lose the way people can approach us and access us in this country, that's one of the things I value about how we do politics. I'm really happy with the precautions that security have always taken. This is a single, individual attack that doesn't appear to be a pattern or organised at all."

Despite being injured, Mr Shaw continued on to Parliament after the attack and went to his meeting.

Agriculture Minister Damien O'Connor was also there.

"I have to give full marks to James, he turned up at cab committee with a black eye and bloody nose so it's true commitment to the job and I hope he comes right quick."

National Party deputy leader Paula Bennett called the attack "horrific".

"No-one should feel unsafe and have that kind of violence against them. Anyone in the public, quite frankly, violence is not okay. You shouldn't be walking to work and have an unprovoked attack like that."

She said there had been three occasions that she'd felt physically threatened in the past.

"I think it is exceptional, even though I've just cited three other cases. I think it's absolutely horrific but also I don't want to go down the path of needing to have police with me permanently either."

Near the scene of the attack, members of the public were equally appalled.

"If you've got something to say to a politician, say it. You don't hit them," said Barbara Stairs.

Andrew Law said seeing politicians out and about in Wellington is an everyday occurrence.

"They're part of the community," he said. "Anything that's politically-motivated that develops into a physical assault is just out of line and uncalled for."

Prime Minister Jacinda Ardern has spoken to Mr Shaw, who said he was doing fine. But she has encouraged him to take whatever time off he has to recover.

"My thoughts are with James and also Annabel. When you go into politics in New Zealand you just don't expect these things to happen, and I know it will be especially challenging for loved ones," she said.

"We have an environment in New Zealand where politicians are accessible - and that's something we should feel proud of. We are after all, here to serve people. But today's events really show we cannot take that for granted.

"I think all of us will probably be united in wanting to ensure we have the kind of political environment where everyone can hold their views, but they can do that safely."

Speaker of the House Trevor Mallard has granted Mr Shaw compassionate leave from Parliament for the meantime.

National's climate change spokesperson Todd Muller said he hopes Mr Shaw recovered really well, and quickly.

He said he had seen views that this is the "new era in New Zealand politics", but he rejected that completely.

"I don't think one man's punch defines a nation's political discourse. It's far from that in this country and in this Parliament and indeed in climate change we're working hard to develop a bipartisan outcome," Mr Muller said.

"I think everyone will be taking stock around their own personal safety."

Information can be shared anonymously via Crimestoppers on 0800 555 111 or Wellington Police on 04 381 2000.

- additional reporting by Gia Garrick