Stalinist North Korea is demanding billions of dollars in compensation for alleged atrocities against prisoners of war and spies formerly held in South Korea, according to state media.
The North filed an unprecedented formal damages complaint to the South's human rights commission through a border office on Friday, the official Korean Central News Agency (KCNA) said.
The complaint insisted Seoul compensate former North Korean long-term prisoners for their time at "nightmarish prisons" run by former authoritarian governments in South Korea.
"The physical damage, ... [not including] mental damage done to them, stands at one billion US dollars according to a preliminary estimate made by specialists of the DPRK [North Korea] in line with international practice," it said on Saturday.
"It would come to several billions of US dollars ... if the damage done to all those unconverted long-term prisoners killed in prisons is put together," it said.
South Korea repatriated 63 North Korean long-term prisoners, mostly prisoners of war and spies who refused to abjure communism, in 2000 after a reconciliation summit with North Korea.
The prisoners had served up to 40 years in jail after being captured during the 1950-1953 Korean War or arrested for spying afterwards.
Citing the repatriated prisoners, the North said they had gone through atrocities, including torture and solitary confinement in 2.5m2 cells, for refusing to renounce their ideology.
"The unconverted long-term prisoners reserve the right to punish the assailants and demand they make apology and compensation for the mental and material losses they suffered as miserable sufferers and victims," it said.
South Korean government officials were not immediately available for comment.
The North, however, has not given a meaningful response to the South's repeated demand to repatriate hundreds of South Korean prisoners of war and civilians held in the Communist state.
More than 540 South Korean prisoners of war are still held alive in the North, according to the defense ministry in Seoul. Another 500 or more South Korean abductees are also said to be held in the North.