SEOUL (AFP) - North Korea on Wednesday (Feb 7) slammed anti-Pyongyang activists for rallying against its participation in the Pyeongchang Winter Olympics, dismissing a dockside protest as a "spasm of psychopaths".

Hundreds of angry South Korean conservatives demonstrated on Tuesday as a ship from North Korea carrying around 120 performers arrived at the eastern port of Mukho.

Some carried pictures of North Korean leader Kim Jong Un with a huge X across his face, while others crumpled the images, stamping them underfoot, and burned both a North Korean flag and a unified Korea flag.

They "ran around like headless chickens, barking that 'the ship of reds came, 'go back to your country' and 'boost the south Korea-US alliance'", Pyongyang's state KCNA news agency said on Wednesday.

"Worse still, they made no bones about besmirching the dignity of the DPRK supreme leadership and burning the flags of the DPRK (North Korea) and the Korean Peninsula," it said.

Any insult to the ruling Kim dynasty always provokes the North's ire.

"They are no more than a group of benighted gangsters inferior to beast," KCNA said, adding that the protesters were "human scum".

The performers spent the night on board the vessel and did not emerge until Wednesday, when they marched off in red coats and were bussed to the Gangneung venue for a rehearsal.

The art troupe, called the Samjiyon Orchestra and numbering 140 in all, is due to perform on Thursday in Gangneung, where the Games' ice events are being held, and in Seoul on Sunday.

The Olympics have triggered a rapid rapprochement on the divided Korean peninsula, after the nuclear-armed North's leader Kim Jong Un expressed a willingness to participate in his New Year speech.

The two Koreas held a rare high-level meeting last month and the North's ceremonial head of state is due to arrive on Friday, the highest-level Pyongyang official ever to visit the South.

Critics in the South allege the North has been allowed to hijack the Pyeongchang Games, and refer to them instead as the Pyongyang Olympics.

But how long the respite in tensions lasts after the Games remains to be seen, especially when the United States and South Korea resume their delayed joint annual military exercises that always infuriate Pyongyang.

KCNA warned on Tuesday the resumption of the drills will throw the Korean peninsula back to "the grim phase of catastrophe".