Copper prices climbed to three-month highs overnight as stronger manufacturing data from top consumer China and the loosening of lockdowns imposed to contain the coronavirus stoked expectations of healthier demand. Benchmark copper on the London Metal Exchange (LME) was up 1.9 per cent at $US5,480 a tonne at 1605 GMT. Prices of the metal, used widely in power and construction, earlier touched $US5,488 a tonne, the highest since March 13. “Barring the tail risks of a second wave (of the virus), we seem to be past the trough, but it is a gradual grind upwards…and we expect metal prices to end the year below where we started,” Capital Economics analyst Kieran Clancy. A private business survey showed China’s factory activity unexpectedly returned to growth in May, while a similar survey for larger Chinese companies showed rising activity in the services and construction sectors. However, both surveys showed export orders shrank. Copper has breached the 100-day moving average at $US5,442. Traders say stronger momentum is needed for an attempt at the upside and resistance at the $US5,590 Fibonacci retracement level. Copper stocks in LME-registered warehouses have risen to 255,725 tonnes, double the level in the middle of January. Sliding tin stocks in LME warehouses, at a one-year low of 2,455 tonnes, and large holdings of warrants and cash contracts are behind the elevated premium for cash tin over the three-month contract. The premium touched a one-year high above $US190 a tonne in May and was last at $US97. Three-month tin was up 1.8 per cent at $US15,690. Aluminium was down 0.6 per cent at $US1,538 a tonne, zinc rose 1.5 per cent to $US2,019, lead gained 0.3 per cent to $US1,678 and nickel added 2.5 per cent to $US12,635.