North Korea on Friday demanded the extradition of the South's spy chief, a Chinese businessman, and unnamed US CIA agents over a supposed conspiracy to assassinate leader Kim Jong-Un.
Last week Pyongyang's powerful ministry of state security said it had foiled a plot by the US and South Korean spy agencies to kill Kim using a biochemical weapon.
The accusations came amid tensions over the North's nuclear and missile programmes and with Washington considering whether to re-designate Pyongyang as a state sponsor of terrorism.
That follows the February killing of Kim's estranged half-brother Kim Jong-Nam by two women using the banned nerve agent VX -- a murder widely blamed on Pyongyang.
The North's Central Public Prosecutors Office said Friday it was opening the prosecution of those responsible for what it called "state-sponsored terrorism" against Kim Jong-Un.
It named South Korea's National Intelligence Service (NIS) director Lee Byung-Ho, an NIS team director surnamed Han, NIS agent Jo Ki-Chol, and Chinese businessman Xu Guanghai as suspects, along with "masterminds in CIA".
"We urge the relevant authorities to immediately detect and arrest and hand over" the wanted individuals, who were "targets of due heavy punishment", it said in a statement carried by Pyongyang's state media.
"None of the brutal perpetrators of hideous state-sponsored terrorism aiming at the removal of the DPRK supreme leadership will survive on this planet," it added, using the acronym for the North's official name.
Rights groups accuse the North of widespread abuses, including an absence of fair trials.
The North is technically still at war with the South and has no diplomatic relations with the US, but China is its sole major ally.
Xu was described as director general of the Qingdao NAZCA Trade Co. Checks by AFP on Chinese databases show a company of that name was founded on March 7 this year, with Xu named as its legal representative.
A spokesman for the NIS said the South's spy agency had no information about the alleged assassination plot.
Pyongyang has said a North Korean citizen named only as Kim was bribed and blackmailed to carry out the attack.
But any attempt on Kim would be extremely difficult to pull off due to supertight security around him and Pyongyang's extensive surveillance of its own population.