The Maritime Union says it's been told redundancies will be on the agenda at mediation with the Ports of Auckland which resumes on Tuesday.
More than 300 union members have been taking industrial action in a dispute over their collective contract.
The union says its members have received a letter advising them redundancies will be discussed.
It says it can't understand why the Ports of Auckland wants to discuss laying off workers, given extra business has been created.
The union says that while the ports lost business when Maersk moved one of its shipping lines from Auckland to Tauranga a fortnight ago, the shipping company OOCL has since announced increased use of the Auckland ports.
Ports of Auckland says that OOCL isn't planning to make any extra ship calls to Auckland, and Maersk's transfer has put the port in serious financial difficulty.
It is calling on the union to cancel the 96 hours of strikes planned before early January.
