The most-traded September iron-ore on China's Dalian Commodity Exchange ended daytime trading 4% higher at 1 175 yuan ($183.78) a tonne, after earlier advancing to 1 191.50 yuan.
July iron-ore on the Singapore Exchange rose 1.5% to $203.65 a tonne by 0703 GMT.
Iron-ore held on to its gains despite China's state planner vowing to step up monitoring of commodity prices and market supervision.
Concerns over iron-ore supply to top steel producer China also buoyed spot prices, with the benchmark 62% material rising to $209 a tonne on Tuesday, the strongest since May 19, based on SteelHome consultancy data.
Iron-ore inventory at Chinese ports dropped to 127.65-million tonnes last week, the lowest since Feb 5, while shipment arrivals were lower than the prior-week and year-ago volumes, according to metals data provider SMM.
