At the port for Ulsan, the industrial hub where much of the strike action has occurred, container traffic has been completely suspended since Tuesday.
At Busan port, which accounts for 80 percent of the country’s container activity, traffic was down to a third of normal levels on Friday, a government official said.
Some 7,500 members, or about 35 percent of the Cargo Truckers Solidarity union, are expected to be on strike on Friday, the transport ministry said.
Reuters and Bloomberg contributed to this report
