Copper fell for a second time in three days as the dollar rebounded against a basket of six major currencies, curbing investor demand for commodities priced in the US currency.

The dollar advanced against 15 of 16 major counterparts as a drop in equities outweighed the Federal Reserve's plan to keep interest rates at a record low. The Dollar Index, a weighted measure of the greenback against the currencies of six main trading partners including the euro and yen, rose yesterday after tumbling as much as 1 percent on Wednesday, the most since Sept 8.

"There is still a lot of uncertainty in the market," Yu Jiaming, an analyst at Jilin Jinchang Futures Co, said from Shanghai yesterday. "The dollar will continue to play a part in determining the direction of commodities."