This year's rise, an average of 2.7 percent, may be a fraction lower than last year's, but it is still well above the official Consumer Price Index (CPI) measure of inflation.

The index works by taking a weighted average of the price of imported iron and domestically produced iron ore to produce a composite number.

Earlier this week, when China released its economic figures for July, the average cost of goods - or Consumer Price Index - was up 6.5 percent, its biggest increase in three years.