US President Donald Trump said on Sunday, without citing evidence, that "certain classes of people" in South Africa were being treated "very badly" and that he would cut off funding for the country until the matter is investigated.

"South Africa is confiscating land, and treating certain classes of people VERY BADLY," Trump said in a Truth Social post.

"The United States won't stand for it, we will act. Also, I will be cutting off all future funding to South Africa until a full investigation of this situation has been completed!" he said.

The United States obligated nearly $440-million in assistance to South Africa in 2023, the most recent US government data showed.

Last month South African President Cyril Ramaphosa signed into law a bill that would make it easier for the state to expropriate land in the public interest.

The law aims to address racial disparities in land ownership that persist three decades after apartheid's demise in 1994.

South Africa's foreign ministry said in response to Trump's post that "we trust President Trump's advisers will make use of the investigative period to attain a thorough understanding of South Africa's policies within the framework of a constitutional democracy."

It added: "It may become clear that our expropriation act is not exceptional, as many countries have similar legislation."

South Africa currently holds the G20 presidency, after which the US takes over.

Last month, Ramaphosa said he was not worried about the country's relationship with Trump. He said he had spoken to Trump after the latter's election victory and looked forward to working with his administration.

During his first administration, Trump said the US would investigate unproven large-scale killings of white farmers in South Africa and violent takeovers of land. Pretoria at the time said Trump was misinformed. It is unclear whether the Trump administration carried out an investigation.

Trump's close ally Elon Musk was born in South Africa. In 2023, Musk replied on X to a video of a far-left South African political party singing an old anti-apartheid song, "Kill the Boer (farmer)", by stating: "They are openly pushing for genocide of white people in South Africa."

"@CyrilRamaphosa, why do you say nothing?" Musk asked.

Musk met Ramaphosa in the US in September last year where they discussed investment in South Africa.