Maritime Union NZ wants an investigation into the working conditions on a British-flagged vessel where a missing sailor is thought to have gone overboard.
It said they have seen widespread unsafe working conditions on overseas vessels including sailors staying on board for over a year, being underpaid and food shortages.
A man is believed to have gone overboard off the British bulk carrier the Berge Rishiri off the Otago coast on Saturday.
The Chinese national was last seen at 8am on Saturday when he finished his shift on the ship, but failed to report for duty that afternoon.
A search of the vessel and coastline was carried out, but it has now been put on hold and will be reviewed to see whether a further search will be successful.
Maritime New Zealand believed there was little chance the person could have survived in the water.
Maritime Union NZ national secretary Craig Harrison said in a statement this kind of incident is more common than many people realise and New Zealand needs to be doing more to protect the welfare of international crews in our waters.
Harrison wants Maritime NZ to investigate whether the crew were having adequate rest breaks and that they were not required to secure any cargo while the vessel is at sea.
Harrison told Ryan Bridge on AM it is not unusual for workers on ships coming into New Zealand to have been kept onboard for long periods of time which can affect their mental health.
"Some of them have been kept on ships for over a year."
Harrison said a lot of the time, Maritime NZ has found crew are underpaid and sometimes there is a shortage of food on the vessels as well.
There are also cases where to save money and time, there is a widespread issue of crew securing cargo while sailing instead of the dock workers securing cargo on board while the ship is docked.
"Envision the ship where they're crawling over the top of log stacks while they are heading out to sea," Harrison said. "It's quite dangerous and if you slip and you go over the side and no one sees you then there is no way of raising the alarm."
Harrison said while these are long-term issues that need to be addressed, at this stage, they are not sure what has happened to the missing sailor.
Maritime Union and the International Transport Workers’ Federation (ITF) say they would like the opportunity to meet the crew and talk about their welfare, and what the shipping company is doing for the crew and family of the lost seafarer.
Harrison says incidents like this can be a red flag of other potential issues aboard ships.
"These crew members are in New Zealand waters, their work is essential for New Zealand, and in our view their rights and welfare are often overlooked."