Copper prices fell on Wednesday, as investors reduced risk exposure amid uncertainty in both demand and supply caused by a power curtailment, while sluggish trade ahead of a major holiday in China also weighed on sentiment.
The most-traded November copper contract on the Shanghai Futures Exchange fell 1.1% to 68,500 yuan ($10,593.53) a tonne at 0409 GMT, while three-month copper on the London Metal Exchange declined 0.3% to $9,241 a tonne.
Power restrictions in China have hurt supplies of some metals in recent months, but electricity curbs recently spread to more downstream sectors and dampened manufacturing, hurting the demand for metals.
A stronger dollar also made greenback-priced metals more expensive and less appealing to holders of other currencies.
China is going on a week-long holiday starting Oct. 1, with investors squaring positions ahead of the break to reduce exposure in a volatile market environment.
"Current power curtailment is still the biggest uncertainty. There are only two trading days before the holiday. It is recommended to control the risk," said brokerage Jinrui Futures in a note.
LME aluminium fell 1.2% to $2,909.50 a tonne, nickel declined 0.4% to $18,490 a tonne and tin was down 0.8% to $35,510 a tonne.
ShFE aluminium rose 0.9% to 22,825 yuan tonne, nickel fell 0.3% to 141,840 yuan a tonne, lead declined 0.8% to 14,385 yuan a tonne while tin rose 1.3% to 273,220 yuan a tonne.
China's top copper smelters set floor treatment and refining charges for the fourth quarter at $70 per tonne and 7 cents per lb, up 27.3% from the third quarter and up from $58 per tonne and 5.8 cents per lb a year earlier.
The global zinc market deficit narrowed to 6,600 tonnes in July and January-July surplus was at 11,000 tonnes, down from a 420,000-tonne surplus in the same period last year, International Lead and Zinc Study Group data showed.