A summary of trading in key commodities markets overseas:
Oil prices sank following a bearish US oil inventory report and amid speculation that the Federal Reserve quantitative easing program could be curtailed sooner rather than later.
The price of US benchmark West Texas Intermediate for July delivery settled at $US94.28 per barrel on the New York Mercantile Exchange, down $US1.90 from Tuesday.
The price of European benchmark Brent North Sea crude for delivery in July closed at $US102.60 per barrel in London, a drop of $US1.31.
The market sell-off followed a US inventory report that showed crude oil inventories declined by 300,000 barrels last week, less than the 600,000 drop forecast by analysts in a Dow Jones Newswires survey.
Even more dramatic, gasoline inventories rose by three million barrels, whereas analysts had predicted a 100,000-barrel decline.
Gold futures extended their losses in electronic trading after minutes from the Federal Reserve's May policy-setting meeting showed board members considered an early end to the central bank's bond-buying program.
A number of Fed officials could be willing to reduce the pace of bond purchases as early as their next meeting if the economy appears to be on a strong, steady path by then, the minutes showed.
However, the minutes also showed there is little consensus among Fed members on when the economy would be ready for the Fed to begin winding down these supportive measures.
Gold, which settled Wednesday in Comex floor trading down $US10.20, or 0.7 per cent, at $US 1,367.40 a troy ounce, fell further in electronic trading after the Fed minutes were released.
The most actively traded contract, for June delivery, was recently down $US21.40, or 1.6 per cent, at $1,356.20 a troy ounce on the Comex division of the New York Mercantile Exchange.
Gold touched a one-week high of $US1,413.30 after Federal Reserve chairman Ben Bernanke, in remarks to Congress, said the Fed's bond purchases yielded "significant benefits" to the economy including cushioning the US against deflationary pressures.
But prices swiftly reversed course, falling to a low of $US 1,365.50, after Bernanke said the Fed could also reduce its bond-buying program in its next few policy-making meetings if economic data warrant it.
Copper has closed higher on the London Metal Exchange (LME), propped up by supply concerns after PT Freeport Indonesia's chief executive said the company still didn't know when it would resume operations following a tunnel collapse at its massive Grasberg gold and copper mine.
Copper rose 2.2 per cent to $US7,533.75 a ton on Wednesday, its highest level since April 12.
The price had been slumping in recent months as investors worried that slowing economic growth in top metals consumer China would result in too little demand for copper to mop up supply.
At the PM kerb close on Wednesday, LME three-month copper was up 1.5 per cent at $US7,474 a ton.
Aluminum was 1.2 per cent higher at $US1,882.50 a ton.
Wednesday's rise came after Rozik Soetjipto of Freeport Indonesia said at a news conference in Jakarta that the company would review the safety of all its mines after the May 14 cave-in at Grasberg and that it hasn't decided when to resume operations.