U.S. President Donald Trump's threat of a 50% tariff on copper imports is raising alarm in the U.S. auto sector, as it could make it even harder for carmakers and suppliers to absorb border taxes and rising costs,

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 the president made earlier this year, when he ordered an investigation into how imports of the metal were affecting national security.

US buyers of copper will pay a high price if President Donald Trump pushes ahead with a 50% tariff on refined metal as opposed to products such as wiring, according to producers and analysts.