President-elect Donald Trump on Monday threatened to impose a 100 percent tariff on the BRICS group nations if they undercut the US dollar.

"We require a commitment... 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 percent Tariffs," Trump wrote on his Truth Social website, referring to the grouping that includes Brazil, Russia, India, China, South Africa and others.

The statement comes after a BRICS summit held last month in Kazan, Russia, where the countries discussed boosting non-dollar transactions and strengthening local currencies. The BRICS group has expanded significantly since its inception in 2009, and now includes countries such as Iran, Egypt and the United Arab Emirates. Altogether the BRICS coalition accounts for a significant minority of the world's economic output.

At the Kazan summit in October, Moscow secured a joint declaration encouraging the "strengthening of correspondent banking networks within BRICS and enabling settlements in local currencies in line with BRICS Cross-Border Payments Initiative."

But at the end of the summit Putin indicated that little progress had been made on launching a possible competitor to the Belgium-based SWIFT financial messaging system.

"As for SWIFT and any alternatives, we have not created and are not creating any alternatives," Putin told reporters at the end of the summit.

He added: "As for a unified BRICS currency, we are not considering that question at the moment."

Trump has vowed to pursue a protectionist agenda, threatening hefty tariffs on neighbors and rivals.

If BRICS countries continue with their plans, Trump warned, they "should expect to say goodbye to selling into the wonderful US Economy," he wrote.

"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."