Copper futures on the Comex surged as much as 17% after US President Donald Trump said he planned to implement a 50% tariff on imports of the metal.

Copper entering the US from other countries is set to face a new tax of 50%, President Donald Trump has said. The decision carries through on tariff threats he made earlier this year, when he ordered an investigation into how imports of the metal were affecting national security.

President Donald Trump said on Tuesday he will announce a 50% tariff on copper later in the day, aiming to boost U.S. production of a metal critical to electric vehicles, military hardware, the power grid and many consumer goods.