The most-traded July copper contract on the Shanghai Futures Exchange also gained more than 1 percent before finishing the session at 46,790 yuan ($7,500) a tonne on Wednesday after a powerful earthquake off the coast of top mine supplier Chile triggered a tsunami alert, which raised supply concerns and set off a volley of technical buying.
"The most immediate risk would be that these tsunami warnings might affect loadings in the ports," said analyst Mark Keenan of Societe Generale in Singapore. Still, there may be room for copper to make more gains after Friday's non farm payroll report, which should shed fresh light on the state of the US economy. "The stock market hit record highs. US data improved. Copper is not only driven by what is going on in China," he added.