Six elderly men who served lengthy jail terms for spying on South Korea have asked to be sent to the North decades after their release, a Seoul unification official told AFP on Tuesday.

The six men, now aged between 80 and 96, served decades in prison while refusing to renounce their communist beliefs.

North and South Korea remain technically at war as the 1950-53 Korean War ended in an armistice, not a peace treaty.

One former prisoner, Ahn Hak-sop, 95, was arrested during the Korean War and jailed for more than 40 years before being released.

A civic group representing the six men said it had asked the government to allow them to be sent to the North on Wednesday, arguing they should be treated as “prisoners of war” whose request should be respected under the Geneva Convention.

“We have received an official request for repatriation. We are looking at various ways to address this, “ an official at the Unification Ministry in charge of inter-Korean affairs told AFP.

The official said more former convicts in similar positions were expected to demand repatriation, adding the government had no precise figure for how many of them remain alive.

The request comes after South Korea’s new President Lee Jae Myung, elected in a June snap election, vowed to improve ties with the nuclear-armed North and resume dialogue.

Lee’s administration has made a series of Pyongyang-friendly gestures, including removing propaganda loudspeakers along the border, which have long irritated the North.

Lee pledged to respect North Korea’s political system and build military trust.

A day earlier, North Korean leader Kim Jong Un’s sister, Kim Yo Jong, however, said the North has “no will to improve relations” with the South.

In 2000, South Korea repatriated 63 “unconverted” former prisoners through the border truce village of Panmunjom during a period of rapprochement — the first and only such event to date.