Fears of a global trade war have risen after Donald Trump threatened to impose 100% tariffs on countries in the Brics group if they create a new currency to rival the US dollar.

Writing on his social media platform, Truth Social, on Saturday, Trump declared that he would also act if they supported another currency to replace the dollar.

“We require a commitment from these countries that they will neither create a new Brics currency nor back any other currency to replace the mighty US dollar or they will face 100% tariffs and should expect to say goodbye to selling into the wonderful US economy,” Trump said.

“They can go find another sucker. There is no chance that the Brics will replace the US dollar in international trade, and any country that tries should wave goodbye to America,” he added.

The warning came less than a week after Trump declared he would impose tariffs on Canada, Mexico and China once he was inaugurated as president.

The Brics group was originally made up of Brazil, Russia, India, China and South Africa and has been joined by Egypt, the United Arab Emirates, Ethiopia and Iran.

Some Brics members have shown interest in de-dollarising the world economy. In October, Vladimir Putin called for an alternative international payments system that could prevent the US from using the dollar as a political weapon. Others, though, fear the consequences of severing relations with the US and other western countries by breaking away from the dollar, which underpins world finance.

A 100% tariff at the US border, if implemented, would drive up sharply the cost of goods from Brics members, fuelling US inflation and destabilising global trade flows.

Stephen Innes, a managing partner at SPI Asset Management, said Trump had laid down the gauntlet with a “blistering proposal” of a 100% tariff.

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“Trump’s recent electoral triumph was heavily fortified by his promise to impose harsh tariffs on foreign imports to the US, advocating for an aggressive 60% tariff on Chinese goods,” he said.

“This hardline approach on trade reflects Trump’s broader ‘America First’ economic policy, which aims to recalibrate global trade dynamics and reinforce US economic sovereignty. As the world watches, the potential for a global trade upheaval looms, setting the stage for a contentious start to Trump’s administration.”