The National Development and Reform Commission (NDRC) of China has blamed leading miners and some traders for leading an increase in the price of iron ore by falsely showing a shortage in the supply.

Without naming the companies, the national planning agency of China said that the top three miners and traders connived to delay shipments and held back stocks in order to communicate to the market that there is some sort of supply shortage. It blamed them for driving up prices by as much as 80 per cent during the previous six months.

The top three miners are Australia's BHP Billiton, Rio Tinto and Vale of Brazil and they account for nearly two-third of the world's total output of Iron ore. BHP Billiton responded to the allegations by saying that it is committed to transparent iron ore market.

BHP Billiton, which is the third largest miner in the world, said that it produced iron ore at full capacity and sold all the material. "We aim to improve transparency by increasing liquidity in the spot market. We sell significant volumes on a spot basis, including through widely accessible trading platforms, irrespective of the iron ore price," it said in a statement.