US estimates are fuelling global supply concerns as inventories are slim and growing areas in North and South America are grappling with unfavourable weather
Powell reaffirmed the central bank's intent to encourage a "broad and inclusive" recovery of the job market, and not to raise interest rates too quickly based only on the fear of coming inflation.
The most-traded July copper contract on the Shanghai Futures Exchange shed as much as 2% to its lowest since April 14 of 66,480 yuan ($10,277.98) a tonne.