South Korea’s government has taken the unprecedented step of invoking tough strike-busting laws to end a six-day stoppage by truck drivers it says is hurting the economy.

The order was approved on Tuesday in a Cabinet meeting called by President Yoon Suk-yeol and targeted about 2,500 drivers of cement trucks among a broader group of truckers participating in the walkout.

The truckers are demanding that the government make permanent a current minimum freight rate system that applies to shipping containers and cement trucking. They are also calling for the minimum pay system to be applied to other truckers including those driving oil and chemical tankers, steel and automobile carriers, and package delivery trucks.

The current minimum freight rate system is due to expire at the end of the year, and the government has offered to extend it for three years, which the truckers say is not enough.

The strike-busting decision, which came after the government failed to reach a deal with unions in talks on Monday, marked the first time a South Korean administration issued an order to force striking transport workers back to their jobs.

Failure to comply can lead to punishments such as cancellation of licences and three years in jail, or a fine of up to 30 million won ($22,550). Critics have denounced the law as unconstitutional, saying it does not provide clear definitions of what acceptable conditions would be for a strike.

Transport minister Won Hee-ryong earlier said the order, if approved, would be executed without delay.

Despite facing the threat of delicensing or even prison terms, the strike’s organisers said they would defy the order and accused Yoon’s conservative government of suppressing their labour rights and ignoring what they described as worsening work conditions and financial strain caused by rising fuel costs and interest rates.

The strike’s damage so far has been largely limited to domestic industries such as construction and there have been no reports of substantial disruptions of key exports such as computer chips and automobiles.

Yoon said the truckers’ strike is threatening to “devastate the foundation of our industries”, citing delays in deliveries of materials such as cement and steel to construction sites and factories. He accused the strikers of illicit activities such as disrupting the work of colleagues who have refused to participate in the strike.

“There’s no way to justify the act of taking the lives of people and the national economy hostage to accomplish their own interest,” Yoon said in the Cabinet meeting.

The strike – the second in less than six months by truckers demanding minimum pay – comes as Asia’s fourth-largest economy is expected to slow to 1.7 percent growth next year, down from previous forecasts of 2.1 percent.

Before the government’s announcement, strike organiser Cargo Truckers Solidarity Union (CTSU) called the start-work order “undemocratic and anti-constitutional”, and evidence of the government’s unwillingness to engage in dialogue.

“The CTSU will not yield to this pan-government crackdown,” the union said in a statement late Monday.

The union plans to hold 16 rallies nationwide on Tuesday, it added.