Shanghai Futures Exchange copper slipped 0.8 percent to 37,630 yuan ($5,643) a tonne on Thursday after China's September trade data showed a sharp decline in exports, raising fresh concerns about the health of the world's No 2 economy and biggest user of metals. China's copper imports fell to 340,000 tonnes in September from 350,000 tonnes in August. Its concentrate imports declined last month by 4.1 percent to 1.39 million tonnes, but were still up a solid 31.9 percent for the year.
"The metal number is weak, but it has been weakening since March. It's no coincidence that (Peruvian mine) Las Bambas has been ramping up this year and more copper concentrate is going to China," said analyst Daniel Morgan at UBS. China's refined metal production jumped by 12.4 percent in August and is up by 8.7 percent this year at 5.498 million tonnes.