Auckland dock workers will walk off their jobs from 10.30pm tonight.
The action will see 320 Maritime Union workers on strike, causing container terminals to close for four days
The port said it has offered a pay increase of 2.5 per cent and has promised not to outsource any further work during a continuous improvement programme.
Chief Executive Tony Gibson said the action will cost the port up to $1.4 million.
He said if the strike goes on for too long, the port's reputation suffers and shipping lines will start to look around for other port stops.
