The Chinese Government has accused BHP Billiton and Rio Tinto of holding back iron ore shipments in order to cause an artificial boost in commodity prices.
Fairfax Media reports iron ore prices have risen 68 per cent since the lows recorded late last year, with prices reaching levels not seen in over 12 months.
The surge has made life harder for Chinese steel mills, and the Government has accused miners and traders of manipulating the market.
“The three major miners and some traders have delayed shipments and held back stocks to control supplies in order to send a fake market signal that there was a supply shortage,” China's National Development and Reform Commission said.
The NDRC also claimed current pricing mechanisms were “unreasonable,” and while Rio declined to comment BHP said it had not held back supply.
BHP said it produced record volumes between July and December and all of the ore was sold.
China has long complained about distortions in the iron ore market, and has made a number of moves to try and lower prices.
This time last year it worked to launch a rival online trading platform, banning banks and financial institutions from the service in an effort to curb speculation.