SEOUL – Young-bok Yoo has not fought in a war since the fateful battle of 10 June 1953 when he was captured by Chinese forces in South Korea’s Gangwon Province. But sitting ramrod straight on a sofa in the Leadership Library of Sookmyung Womens’ University, Seoul, he has the bearing of an old soldier.

Such robustness has helped him survive the Kumduck and Dong Am mines where he worked as a laborer and then a surveyor. The former is North Korea’s largest and oldest mine, location of vast deposits of copper and zinc. Like so many of the 60,000 South Korean POWs forcibly detained after the Panmunjom Armistice, its dank and choking shafts were to be his unexpected destination when fighting ended. Mr Yoo is one of just a handful of ex-POWs to have escaped North Korea since the late 1990s.