Bill Clinton’s mission to free two US reporters held in Pyongyang has caused consternation in South Korea, where the government is accused of not doing enough to get its own citizens back.

North Korea has seized hundreds of South Koreans since the Korean war in the early 1950s. This year the communist state has detained an employee of Hyundai Asan, a South Korean company with interests in the North, and four squid fishermen who strayed across the maritime border when their navigational system broke.