A financial cost is being felt in Canterbury as Lyttelton Port workers consider more industrial action.
The Rail and Maritime Transport Union (RMTU) is threatening up to another three weeks of strike action next month.
"They want to be safe and healthy at work, to be treated the same as other workers at the port, and for their employer to negotiate with them in a constructive, respectful way," union organiser John Kerr said on Friday.
"Lyttelton Port Company has made a deal with the other union on site and refused to extend it to our members. They've made changes to the hours of work at the port which increase the risk of fatigue. And they're refusing to budge despite us meeting with them multiple times and providing up to eight different options to resolve this dispute."
Dieter Adam from the Manufacturers' Network says businesses can't handle ongoing industrial action for much longer.
"The operational disruption is incredible. There's freight that can't go on the road, so some people are waiting for chemicals and have to stop processing because they can't get those goods in," he told Newshub.
Mr Adam says further action will likely kill off some businesses, but he's optimistic a deal can be struck.
"I've got no idea how serious the consequences will be [if they don't], but I know now that people are increasingly having to slow down or stop production - even at the current stage."
Mr Adam accused members of the RMTU of bullying port board members by handing out pamphlets containing the names and addresses.
"It's a level of intransigence that I find quite frustrating."
National's workplace relations spokesperson Michael Woodhouse accused the union of "thuggish" behaviour, RNZ reported.
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The present RMTU strike ends on Sunday. It follows industrial action by members of the RMTU who work on Auckland's trains.