The sharp rise in the price of copper over the past five weeks has been driven in part by the unwinding of bearish bets made by large investors - among them, China’s State Reserve Bureau and Ospraie Management, a US hedge fund, according to market participants.

The base metal has climbed more than 75 per cent this year, rising 36 per cent since the start of April and hitting a record $7,780 a tonne on the London Metal Exchange on Friday. The past few weeks have seen several investors with large short positions capitulate and cover their positions.