Shanghai Futures Exchange copper slipped 0.09 percent at 45,770 yuan ($6,642) a tonne on Tuesday after copper dipped on indications of healthy supply. Imports of refined zinc to China increased 21 percent in April to 47,469 tonnes year-on-year while shipments of ore and concentrates jumped 44 percent, customs data showed. Some investors have been counting on shortages to emerge after a series of mine closures and suspensions last year, but evidence of tightness has been slow to emerge.
"Those import numbers showing that China's importing more in April could be evidence showing things are tightening up in China, which is the biggest consumer," said Robin Bhar, head of metals research at Societe Generale. Copper imports in China, however, fell 41 percent, partly due to tighter credit.