The head of Port Nelson says poor training among contractors can affect safety standards at ports.
In the latest in a spate of accidents at Lyttelton Port of Christchurch, a man was injured on Saturday at the city depot yard in Woolston after a falling container crushed the machine he was operating. Two deaths occurred at the South Island port in late 2013.
The Rail and Maritime Union has said the increase in accidents reflects the fact the port has not had a fulltime health and safety manager for more than a year.
But Port Nelson chief executive Martin Byrne said the use of certain contractors can threaten safety standards.
"You can obviously spend a lot of time with your own staff on health and safety and go through procedures, but when you have third party people coming in who are operating within your area, to some degree you are reliant on how those companies operate as well."