At night, after hanging around doing little at work all day, Oh Man-bok would often go home and do what many television viewers around Asia do - switch on one of the South Korean -dramas that in recent years have swept across the region as part of a "Korean wave".

But Mr Oh was watching them in North Korea, where Kim Jong-il has for years restricted access to outside information as part of his efforts to convince the -reclusive state's 23m people that they live in a socialist paradise.