A man was killed at Lyttelton Port on Monday during the loading of coal onto a ship at Cashin Quay.
Lyttelton Port Company said emergency services were called to the site at about 9.30am.
The tragedy happened just six days after the death of 26-year-old Atiroa Tuaiti at the Ports of Auckland.
Tuaiti's death prompted a number of sector unions to request an inquiry into the safety of New Zealand's ports.
The Maritime Union, Rail and Maritime Transport Union, Council of Trade Unions and the Merchant Service Guild collectively asked for the inquiry last week.
Council of Trade Unions national secretary Craig Harrison said the latest tragedy further reinforced the need for widespread review.
"There's been ongoing prosecutions of some of the companies in the industry, so we've reached that stage where everyone's just had enough of it," he said.
Harrison said the sector was disproportionately unsafe, and the government needed to hear the experiences of port workers to understand the weight of the problem.
"There's thousands working in [construction] over here in New Zealand, and they don't feature anywhere near like the port industry does."
National Party transport spokesperson Simeon Brown also supported an inquiry and said the current regulations were failing.
"We've had significant increase in regulations around health and safety across New Zealand workplaces, and actually, is that actually working, is that actually making it safe for these workplaces."
But despite accumulating calls for an inquiry, there was still no confirmation one would take place.
Minister of Workplace Relations and Safety Michael Wood said he was taking the union's request seriously, but was waiting for advice from agencies to decide whether it was the right move.
"The important thing here is that we don't just have an inquiry for an inquiry's sake, that if we go down that track that it's adding something to our understanding and actually pointing us in the right direction."
Wood agreed that the number of port fatalities in New Zealand was disproportionate and said a key safety issue was fatigue resulting from long hours, and high pressure on workers.
"Obviously having a second death in the sector in such a short succession like this, really does have to focus our minds on doing everything that we possibly can to be reducing the number of these incidents."
The recent deaths have been tough for Gareth Fraser, whose brother-in-law died in 2020 after he was crushed when a container was dropped at the Ports of Auckland.
"It's brought up a lot of anger, a lot of sadness, it's sort of put my sister and the children back into that moment of when their husband and father was taken away from us," he said.
He was appalled the ports had continued to operate without immediate change.
"I think there's a lot more that's needed, you know, first and foremost, they need to stop all operations at the Ports of Auckland, until they can ensure that no more workers are going to be killed.
"We've got these young men that are working on these ships that are still moving in water while they're being berthed - there's no safety harnesses or any sort of safety measures that protect these men."
The identity of the man who died at Lyttelton Port on Monday has not yet been revealed.
Three separate investigations are underway into the incident with police, Lyttelton Port Company, and the Maritime Union.
