Copper retreated on Wednesday as profit-taking pulled the commodity from four-week highs ahead of a key U.S. Federal Reserve policy meeting later in the day.
Benchmark copper on the London Metal Exchange was down 0.7 percent at $4,758 a tonne by 1025 GMT, paring small gains made in the previous session.
The U.S. central bank is widely expected to hold interest rates unchanged at 0.25 percent to 0.50 percent, but could hint at a rate hike in December, which would strengthen the dollar and pressure metals.
A higher U.S. currency makes dollar-denominated commodities more expensive for non-U.S. firms, a relationship used by funds to generate buy and sell signals for industrial metals.
"There is some short term profit taking, the bulls were hopeful that after last Wednesday's gains momentum would shift to the upside. However, we're ahead of the Fed so some profit taking is to be anticipated," Kash Kamal, senior research analyst at Sucden Financial.
He said benchmark copper held on to support around $4,750 this week but a higher dollar could put near term pressure on prices.
In other central bank news, The Bank of Japan shifted key policies to target interest rates instead of its money-printing program, and recommitted to reaching its elusive 2 percent inflation goal as quickly as possible.
But as indicators improve from the world's top metals user, China, it appears more likely that January marked a floor for prices, Macquarie said in a report.
"The latest data points confirm that Chinese construction activity remains in a positive trend, while we are in a nascent global industrial production recovery," Macquarie said.
Nickel rose 0.15 percent to $10,325 a tonne after the Philippines said it would suspend more than 10 additional mines in an ongoing environmental crackdown on the sector.
It delayed for a second time the announcement of which companies will be shut to Sept. 26.
Tin fell 0.23 percent to $19,430 a tonne and lead fell 0.78 percent to $1,964.50 a tonne.
Aluminum was flat at $1,576 a tonne, while zinc slipped 0.41 percent to $2,290.50 a tonne.
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