The most-traded copper contract on the Shanghai Futures Exchange dropped as much as 1.4 percent to a one-month low of 36,500 yuan a tonne on Tuesday. It closed the day down 0.7 percent at 36,730 yuan. "Over the past week, copper prices have converged with our view that the recent rally was unsustainable, as it was built on transient technical factors and poor fundamentals," Barclays said in a research note.
Recent upbeat Chinese data has failed to lift copper prices, which some analysts say is an indication the metal's rally in the beginning of the year was overdone. While China's manufacturing activity unexpectedly expanded for the first time in nine months in March, factories still shed jobs at a significant rate.