US President Donald Trump has warned that countries which side with the policies of the Brics alliance that go against US interests will be hit with an extra 10% tariff.
Trump has long criticised Brics, an organisation whose members include China, Russia and India, which was designed to boost countries' international standing and challenge the US and western Europe.
"Any country aligning themselves with the Anti-American policies of BRICS, will be charged an ADDITIONAL 10% tariff. There will be no exceptions to this policy," Trump wrote on social media.
A deadline for countries to agree a tariff deal with the US had been set for 9 July but US officials now say they will begin on 1 August.
So far, the US has only struck trade agreements with the UK and Vietnam. However, Britain and America have still not reached a deal over taxes for UK steel imported by the US.
Since taking office in January, Trump has announced a series of import taxes on goods from other countries - arguing they will boost American manufacturing and protect jobs.
In April, on what he called "Liberation Day", he announced a wave of new taxes on goods from countries around the world, although he quickly suspended his most aggressive plans to allow for three months of talks up until 9 July.
Asked whether the taxes would change on 9 July or 1 August, Trump said on Sunday: "They're going to be tariffs, the tariffs are going to be tariffs."
He added that between 10 and 15 letters would be sent to countries on Monday advising them on what the new tariff rate will be if a deal had not been reached.
US Commerce Secretary Howard Lutnick clarified that the taxes will come into force on 1 August.
On Sunday, Treasury Secretary Scott Bessent had told CNN: "President Trump's going to be sending letters to some of our trading partners saying that if you don't move things along, then on August 1 you will boomerang back to your April 2 tariff level."
Trump's threat to countries working with Brics nations emerged after members criticised US tariff policies as well as proposing reforms to the International Monetary Fund (IMF) and how major currencies are valued.
Last year, the list of Brics members expanded beyond Brazil, Russia, India, China and South Africa to include Egypt, Ethiopia, Indonesia, Iran, Saudi Arabia and the United Arab Emirates.
The countries in the bloc account for more than half of the world's population.