(Bloomberg) -- A major umbrella union joined a protest by South Korean truckers, broadening a work stoppage that is disrupting global supply chains and hitting local exporters. 

The Korean Confederation of Trade Unions will stage demonstrations at 16 places Tuesday at 2 p.m. to support striking truck drivers, according to the union’s website. The union, which has about 1 million members including metal workers in autos, shipbuilding and chip industries, didn’t disclose how many participants will be at the protests. 

Calling for better wage systems since Nov. 24, the truckers’ strike is straining supply chains at Korean exporters as they are blocking ports and entrances of plants. The government has issued orders in an attempt to force drivers in key industries to return to work, yet just 25% of container shipments recovered to the normal levels as of 5 p.m. Sunday, according to the Ministry of Oceans and Fisheries. 

Starting Monday, the trade ministry will ask shipping companies and cargo owners whether their truck drivers are following the government’s orders, the ministry said in a statement Sunday night. The truckers’ union said it will continue the protests, blaming the government for “violently cracking down on strikes.”

South Korea President Yoon Suk Yeol’s approval rating rose for the second week amid his hard-line stance on the strike, a survey from Realmeter showed. Yoon compared the truckers’ strike to “a threat like North Korea’s nuclear activities,” Yonhap News Agency reported, citing a recent meeting between the president and top officials.

--With assistance from Sangmi Cha.

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