LONDON: Copper prices extended gains on Wednesday to the highest level in nearly four weeks on hopes that China will inject more stimulus into its economy, boosting metals demand.

Three-month copper on the London Metal Exchange (LME) added 0.2% to $8,352 a metric ton in official open-outcry trading after touching its strongest since May 11 at $8,418.

“What’s driving the gains seems to be a vague hope that China’s going to stimulate the economy more,” said Dan Smith, head of research at Amalgamated Metal Trading.

Also boosting the market was a dip in the US dollar index. A weaker US currency makes dollar-priced commodities more attractive for buyers using other currencies.

Among other metals, LME aluminium rose 0.1% in official activity to $2,213 a metric ton, zinc jumped 2.6% to $2,380, lead gained 0.6% to $2,038, nickel advanced 0.8% to $21,140 while tin was down 0.3% at $25,550.