South Korea is in "chaos" after President Yoon Suk Yeol's brief imposition of martial law, North Korean state media said on Wednesday in its first comments on the political upheaval.

Yoon suspended civilian rule on Tuesday last week and sent special forces and helicopters to parliament before lawmakers forced him to rescind the decree.

"The shocking incident of the puppet Yoon Suk Yeol, who is facing impeachment and a governance crisis, suddenly declaring a martial law decree and unhesitatingly wielding the guns and knives of its fascist dictatorship wrought chaos across South Korea," North Korean state media said in a commentary.

"The international community is sternly watching, with assessments that the martial law incident exposed vulnerabilities in South Korean society," it added.

"Commentators described Yoon's abrupt declaration of martial law as a desperate move and that Yoon Suk Yeol's political life could face an early end."

In declaring martial law on December 3, Yoon said it would safeguard South Korea "from the threats posed by North Korea's communist forces and eliminate anti-state elements plundering people's freedom and happiness".

Relations between the two Koreas have been at one of their lowest points in years, with the North launching a flurry of ballistic missiles in violation of UN sanctions.

It also has been bombarding the South with trash-carrying balloons since May, in what it says is retaliation for anti-Pyongyang propaganda missives sent North by activists.

Former defence minister Kim Yong-hyun, who was arrested on Tuesday, has been accused by opposition lawmakers of calling for strikes on sites from which North Korea was launching balloons carrying trash, an order reportedly refused by his subordinates.

The opposition plans to bring another motion to impeach Yoon to a vote on Saturday. (AFP)