Spot iron ore prices fell to the lowest since late December as slower steel demand in top market China sapped buying interest for the raw material. Iron ore has lost more than 9 per cent since hitting a 16-month high in mid-February after Chinese steel mills eased up on restocking given rising inventories of steel products that pointed to weak end-user demand. Slower Chinese appetite since last year is prompting top iron ore miners to curb costs to boost their profits as prices fall. Rio Tinto has cut staff at its multi-billion Simandou iron ore project in Guinea by 90 per cent, essentially freezing its investment, according to government sources in the West African country. Benchmark 62-per cent grade iron ore for immediate delivery to China fell 1.5 per cent to $144.10 a tonne on Monday, the lowest since Dec. 28, based on data from price provider Steel Index. Before hitting its weakest this year, iron ore peaked at $158.90 on Feb. 20, its loftiest since October 2011.