First Union Dunedin organiser Shirley Walthew said about 30 Dunedin members went into the supermarket and handed out pamphlets, before gathering outside the store to protest the wage gap between New World’s North Island stores and its South Island stores.
Ms Walthew said the two-hour picket was relatively peaceful.
However, Centre City New World owner Craig Nieper said "a number" of the protesters were trespassed from the store because of their behaviour.
None of them were employees of the supermarket, he said.
Ms Walthew was one of those trespassed.
"I don’t know why they trespassed me, because I was quite happy to leave the car park.
"I think it was a bit heavy-handed."
She criticised Foodstuffs’ stores in the South Island for paying their work force up to $2 less per hour than workers in unionised stores in the North Island.
"Working people are entitled to a wage they can live on. They’re also entitled to some fairness — there’s no excuse for paying South Islanders less than North Islanders."
Ms Walthew said the picket was part of several actions taking place across the South Island to highlight how several store owners were refusing to negotiate secure work and living wages for supermarket workers.
Mr Nieper declined to talk about the wage negotiations because his store was engaged in a "good faith bargaining process" with First Union.
"As such, I am unwilling to carry out this process in the public arena, as I do not believe it fits with the good faith process."
A police spokesman said no arrests were made in connection with the protest action.
