The Maritime Union is renewing calls for a national inquiry into port safety.
Two employees of the cargo handling firm C3 were injured on board a container vessel at the Port of Timaru yesterday morning.
One of them, a man in his 50s, suffered serious back injuries as the result of a fall, and remains in Christchurch Hospital. The other man was treated at Timaru Hospital.
The union's national secretary, Joe Fleetwood, said the port sector had systemic health and safety problems, compounded by long, irregular shifts and more time pressure being put on workers.
Maritime New Zealand is investigating the incident.
The Port of Timaru's container terminal manager, John Bromley, said the port would wait until C3's investigation was completed before deciding whether or not it needed to do its own.