China and North Korea have been long-time allies. Mr Kim's rapid visit to the injured people - and the reporting of it - is likely to be seen in part as a way of protecting his image among the Chinese population.

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Chinese tourists make up an estimated 80% of foreign tourists to North Korea - providing an important source of currency for Pyongyang.

Mr Kim earlier this year visited Chinese President Xi Jinping in Beijing, his first known foreign trip since he took office in 2011.

China is responsible for virtually all of North Korea's food and fuel aid and by many measures, can be considered its most important partner.

North Korea recently announced it was halting all nuclear and missile tests, as it builds up to major summit with the leaders of South Korea and the US.