China suspended key rail freight services into North Korea last week after 1,800 wagons carrying food aid and tradeable goods crossed into Kim Jong-il’s hermit state but were never returned.

Absconding with Chinese wagons would be a strange move for North Korea because Beijing is Pyongyang’s closest political ally and biggest provider of food, goods and oil. Analysts monitoring North Korea said Chinese officials had privately complained to them that the North Koreans were dismantling Chinese wagons and selling them back as scrap metal.