Police have detained one woman outside a defence forum in Palmerston North at protests organised by groups calling the event a "weapons expo".
The New Zealand Defence Industry Association Forum chairman says the conference is not a weapons expo and labelling it so was a cry for attention.
A small group of protesters have gathered in Featherston St, ahead of a march to take place in the city square at 11.30am.
A strong police presence included extra officers brought in from Whanganui.
Protestors have prevented a bus load of NZDIA members from getting off the vehicle.
The police were needed to form a cordon to allow them to exit. One woman who lay beside the bus and refused to move has been taken away by police.
Protest organiser Valerie Morse said the intention was to blockade and delay delegates attending the event.
"The peace movement is using tactics of non-violent direct action to stop war at its source: with the people who directly profit from waging war."
"We expect that the police and security will respect the human rights of people who are standing against war."
"Actions will continue over the next two days."