Chile's power grid and major copper mines slowly came back online on Wednesday morning after a major outage hit the world's top producer of the metal, with power firms working to restore the system to full operation,

Copper futures (HG1:COM) rose nearly 4% on Wednesday, extending gains to a second trading session after U.S. President Donald Trump ordered an investigation into potential tariffs on copper imports. Prices also got a boost from expectations of supply disruptions after Chile was hit with a widespread power outage,

A major power outage in Chile has disrupted copper production at some of the world's largest mines, prompting a state of emergency.