The FT said gold bars weighing 1kg and 100 ounces have been classified as subject to tariffs by the US customs border protection agency – threatening to upend global trading of the precious metal.

In reaction, gold for December delivery reached an all-time high at US$3,534.10 an ounce (31.1 grams) on the Comex, the world’s biggest futures market.

Gold, seen as a safe haven investment, has already reached record highs this year on tariff concerns and geopolitical unrest.

Commerzbank analyst Carsten Fritsch said today that tariffs on bullion “would have serious implications for the gold market”, with key supplier Switzerland already subject to hefty US tariffs.

“One-kilo bars are the most common form traded on Comex and comprise the bulk of Switzerland’s bullion exports to the US,” the FT said.

Fritsch noted that “gold bars of this size imported from Switzerland into the US would be subject to a 39% tariff”.

The amount, one of the highest tariffs imposed by Washington, entered force yesterday.

“Switzerland is a major supplier of gold bars because it is home to many gold refineries that melt down gold into specific bar sizes,” Fritsch pointed out.

Ole Hansen, head of commodity strategy at Saxo bank, added that “the US futures market is often used by bullion banks globally as a hedging tool for transactions in the physical bullion market”.