Interior Minister Lee Sang-min speaks during a government meeting on Nov. 28. Yonhap

The government will invoke an executive order to force striking truckers to return to work in the event that their ongoing walkout poses a serious threat to the national economy, Interior Minister Lee Sang-min said Monday.

The remarks came as a strike by unionized truckers entered its fifth day Monday, demanding the government extend temporary rules guaranteeing minimum freight rates, citing high fuel prices.

As of Saturday, more than 5,000 truckers from some 130 workplaces nationwide were taking part in the strike, bringing the average container movement at major ports across the nation to 28.1 percent of the normal level over the last four days, according to the government.

"The government will respond sternly based on a zero-tolerance principle in accordance with the laws and rules," the interior minister said during a government meeting.

"If a serious crisis is expected to hit the national economy due to the latest strike, the government plans to invoke the return-to-work order while setting up an emergency police response system to ensure protection for normal transportation activities," Lee also said.