The state planner and market regulator said in a statement that they had warned iron ore information providers to ensure the accuracy of their release and should not fabricate or drive up prices.
The most actively traded iron ore futures on the Dalian Commodity Exchange, for May delivery, dived as much as 5.8% to 782 yuan ($122.94) per tonne, the biggest percentage loss since Dec. 3.
"As authorities are paying close attention to iron ore, prices could weaken affected by market sentiment," GF Futures analysts wrote in a note.
Other steelmaking ingredients were mixed, with Dalian coking coal futures dipping 0.04% to 2,412 yuan a tonne as of 0306 GMT, while coke prices up 0.6% to 3,092 yuan per tonne.
Construction material steel rebar on the Shanghai Futures Exchange slipped 0.5% to 4,879 yuan a tonne.
Hot rolled coils futures edged 0.1% lower to 5,035 yuan per tonne.
Shanghai stainless steel futures, for March delivery, gained 0.8% to 18,150 yuan a tonne.
 "iron ore")
