Mediation has begun between the Ports of Auckland and the Maritime Union in the hopes of averting strike action.
The union has given notice of a 24-hour strike on 2-3 December, which will affect the port's two container terminals, road, rail, shuttle and engineering services.
The parties failed to reach agreement on Wednesday and talks will continue on Friday.
Ports of Auckland managing director Jens Madsen says he is concerned this will affect New Zealand's reputation given the economic situation and the busy pre-Christmas period.
The union says one of the main points of dispute in the collective employment agreement, which expired in 2006, is the use of casual labour.