More than two dozen protesters have been arrested outside the annual New Zealand Defence Industry Association conference in Wellington.
The protest was organised by Peace Action Wellington, which wanted to disrupt the meeting and what it called "the business of war".
About 150 people blocked attendees from getting into the conference this morning.
Police said officers did not use excessive force to arrest the 28 protesters, who have been charged with trespassing, obstruction and disorderly behaviour.
Anglican Bishop of Wellington Reverend Justin Duckworth was at the protest to show his concern that the city was hosting the conference.
"I kind of think as Wellington is a peace city, for us to host a weapons conference is a total hypocrisy, so I'm here as the Bishop of Wellington to show my disgust that we would do this," he said.
The protesters were angry that the Wellington City Council had allowed one of its venues to be used for the forum.
The forum's principal sponsor is Lockheed Martin, which, among other activities, makes nuclear weapon control systems.
One protester, who did not want to be named, said many people at the conference were warmongers.
"You've got to be standing up against these people because these guys are letting it happen, and I couldn't sleep at night if I didn't stand up for people who don't have a voice in the world, so I'm here."
But Defence Minister Gerry Brownlee said there was nothing wrong with the New Zealand Defence Industry Association holding its annual conference at the TSB Arena, and said those at the conference were not discussing the business of war.
"You've got to have a look at what sort of conference it was - these are suppliers to the New Zealand Defence Force (NZDF), so they supply everything from paper cups to socks."
Mr Brownlee said none of the companies at the conference supplied weapons or arms to the defence force.
An Australian man trying to attend the conference, and who wanted to remain nameless, said he supported people's right to protest.
"Everyone's entitled to their opinion in countries where they're allowed to have their freedom, but they've got to realise freedom was fought and won for.
"So good luck to them, let them have their opinion but they should recognise how they got it."
Peace Action Wellington spokeswoman Valerie Morse said the council must take a stand.
"We took the issue to the mayor, Celia Wade-Brown, but we didn't get a positive response from her," she said.
"We think it's appalling that in Wellington, which is a peaceful city, something like this would be hosted."
She described the forum as a 'weapons conference'.
"Lockheed Martin is very proud of its record and involvement in the Trident nuclear missile system, which it still manages in the United States.
"This is a conference of 200 of the world's largest weapons manufacturers and its purpose is for these companies to sell more weapons around the world."
But New Zealand Defence Industry Association chairman Bernie Diver said talk of weapons would only be a small part of the forum.
"Lockheed Martin is a very large organisation - it predominantly provides logistics and warehouse management in New Zealand.
"This is not a weapons conference per se. It's about industry supporting [the New Zealand Defence Force] to allow it to be the best organisation it can be."
Council to consider options next year
The Wellington City Council has proudly boasted of its anti-nuclear weapons stance in the past.
To mark the 70th Anniversary of the nuclear bombing of Hiroshima, the council on 6 August unanimously endorsed a statement by world politicians and religious leaders calling for the abolition of nuclear weapons.
Council spokesman Richard Maclean said he did not think there was a conflict of interest.
"We're certainly aware that there are people in the community who are unhappy with this event - which we have held at council venues for a number of years," he said.
"But we try to take a non-judgmental approach to events, as long as they don't break any laws."
Nevertheless, the council would look at whether it does the same again next year, he said.
The NZDF said it respected the rights of protesters, and believed the same respect should be shown to those at the forum and its organisers.
NZDF chief Tim Keating was expected to attend the forum.