Logistics staff at the Lyttelton Port will continue rolling strike action for several weeks.
Discussions between the port company and the 11 workers broke down on Tuesday. The staff had already voted for a walkout on Friday night, and that will now be extended.
The staff are involved in the directing of ships and have been bargaining with the port since Christmas.
Rail and Maritime Transport Union's South Island organiser John Kerr told Radio New Zealand's Morning Report programme it would take only a few dollars to meet the workers demands.
Lyttleton Port chief executive Peter Davie has not commented on the latest move. He has previously said the action would affect only one of three daily shifts, and he expected work to continue as normal.
