China’s statistics pose multiple difficulties for analysts, especially since they were called “man-made” by the current premier, Li Keqiang, in a US diplomatic cable.

The country grew at 7 per cent in the second quarter of this year according to Beijing, but commodity prices, especially metals, have fallen to some of their lowest price levels in six years. That is leading analysts to take a new stab at working out just how large the slowdown in commodity demand really is in the world’s biggest consumer.

Working out China’s demand is not easy, however. In many cases, data are obfuscated by imports from Hong Kong, a Chinese territory, and the practice of importing metal as collateral to obtain bank loans. It is also unclear how many stocks of metal and other commodities are sitting at warehouses not monitored by exchanges.