The traditional coal mining region where output reached close to a billion tonnes last year has reduced the number of coal mines to roughly 500 from more than 1,300 in 2005 reports China Daily.

All coal mines with an annual capacity of less than 300,000 tonnes have been ordered to shut down, according to the regional department of land and resources.

Inner Mongolia is also an important centre for the country's rare earths industry. China – responsible for more than 90% of the global supply of the 17 elements used in a variety of industries including green technology, defence systems and consumer electronics – a few years ago embarked on a crack-down on illegal rare earth mines and consolidation of the industry under a few large producers.

A recent report by state news agency Xinhua painted  a particularly grim picture of China's rare earth industry which belies the notion, held by many in the West, that China's crackdown has more to do with managing supply and extracting lofty profits than it is about cleaning up a notoriously dirty business.