Labour productivity at Maersk's APM Terminals in Gothenburg has fallen to 80 per cent in the last six months due to a conflict with the Swedish Dockworkers' Union.
It could drop to 40 per cent in the coming days as APM Terminals plans a partial lockout in response to the dockers' go-slow.
The port handles half of Sweden's container trade, and now SKF AB, the world's largest maker of ball bearings, is warning that it may need to permanently relocate shipments to ports in northern Europe.
Stora Enso Oyj, whose paper, pulp and sawed-wood products account for 10 per cent of the terminal's volumes, is calling on the government to resolve the conflict.
"The port's operation is crucial for us to be able to ship our forestry products to global markets in a cost-efficient way," the company said in a letter to the government.
Having to relocate shipments from the busiest and largest port in Scandinavia could pose a major challenge for an economy such as Sweden's, where exports represent 44 per cent of economic output.
Exporters would probably have to truck goods German ports such as Hamburg and Bremerhaven, Rotterdam in the Netherlands or Antwerp in Belgium. That would add time and drive up costs.
The union has rejected several proposals over the past year and its continued action is now having "severe national consequences," APM Terminals Gothenburg CEO Henrik Kristensen told Bloomberg.