In February it was revealed that Liu Zhijun, the head of China's Ministry of Railways, had been placed under investigation for "severe disciplinary violations", the usual official terminology for corruption. He becomes the most senior official to be removed from office on graft grounds since 2006. Over Rmb2.5trn (US$370bn) has been invested in railways since he was appointed in 2003, and there is speculation that the latest investigation may have been prompted by misuse of funds associated with the ongoing roll-out of China's high-speed rail lines.

Political factors are also likely to have been at play. Liu Zhijun managed to keep his position until recently despite the fact that his brother, Liu Zhixiang, a senior railway official in the city of Wuhan, was convicted in 2006 of charges that included corruption and hiring an assassin. In 2008 he also saw off efforts led by China's vice-premier, Li Keqiang, to incorporate the railway ministry into a broader Ministry of Transport. It is possible that his removal reflects manoeuvring by senior leaders ahead of the 2012-13 handover of power to a new generation of politicians.