Up to 150 jobs could be cut if a proposed merger between stationery companies OfficeMax and Staples goes ahead, says First Union.
The US-based global investment firm Platinum Equity recently bought Staples and was looking to acquire its main competitor, OfficeMax.
First Union general secretary Robert Reid said the merger would not be in the public or workers' interests, and has called on the Commerce Commission to investigate.
"The union is concerned that as many as 150 Kiwi jobs could go as a result of the merger if it were to go through," Reid said.
"It will also eliminate competition in the office supply sector in New Zealand."
"First Union is calling on the Commerce Commission to investigate the proposed merger and not allow it to proceed," he said.
In 2015, the commission granted approval for the merger, however, Reid said further evidence of the anti-competitive nature of the merger had arisen, saying the current proposal was very different from the one approved two years ago.
"These two companies are currently both profitable and viable stand-alone businesses employing hundreds of workers. It needs to stay that way," Reid said.
According to Reid, there were other parties interested in purchasing OfficeMax and running it as a stand-alone business.
He said allowing the merger to go ahead "made no sense for the economy or consumers".