Copper prices hit two-month highs overnight lifted by worries about supplies from Chile due to the possibility of a strike, BHP Billiton cutting its forecast for copper output and a weaker dollar.
Benchmark copper on the London Metal Exchange ended little changed at $US5942 from $US5943 on Tuesday after earlier hitting a session high of $US5973.
Traders said BHP Billiton cutting its full-year copper output forecast by 2 per cent had reinforced concerns about tighter supplies this year, but that the recent run higher had persuaded some funds to take profits.
Unionised workers at BHP Billiton-run Escondida in Chile, the world's biggest copper mine on Tuesday rejected the company's latest wage offer and asked workers to vote for a strike and prepare for an extended conflict.
Workers at the mine, which produced 452,000 tonnes of copper in the six months to end-December, will vote on the proposal between January 27-31.
"The news from Escondida has encouraged buying, there is an expectation the Chinese will pile back into copper after the New Year and the dollar is softer," said Citi analyst David Wilson.
A lower US currency makes dollar-denominated commodities cheaper for non-US firms, potentially boosting their demand.
The Chinese New Year holiday from January 27 - February 2 means subdued manufacturing activity and weaker demand for industrial metals.
Three-month aluminium closed down 1.8 per cent at $US1833.5 a tonne from a 20-month high at $US1883 on Tuesday. It has been boosted by talk of output cuts in top producer China.
"As wintertime pollution surged in Beijing, news reports began circulating that winter production restrictions could spread from the cement and steel industries into aluminum," JPMorgan analysts said in a note.
"Thirty percent of aluminum smelting and 50 per cent of alumina refining capacity in Henan, Shandong and Shanxi provinces could be potentially affected ... the three provinces combined account for about 36 per cent of the total current Chinese aluminum capacity."
China's aluminium production capacity is estimated at around 40 million tonnes. Analysts say the capacity cuts if approved would be rolled out for the next winter.
Lead fell 0.1 per cent to $US2390 a tonne, but still near the six-week high of $US2394 hit on Tuesday. Expectations of stronger demand from car battery makers have boosted prices.
Zinc slipped 0.9 per cent to $US2801, tin rose 0.1 per cent to $US20,425 and nickel ceded 0.9 per cent to $US9700.