The US president says he has refused to attend the group's upcoming summit in Johannesburg

US President Donald Trump has blasted South Africa, saying the country "shouldn't even be" a member of the G20, where it currently holds the rotating presidency.

During South African President Cyril Ramaphosa's visit to Washington in May, Trump accused his administration of tolerating a "genocide" of Afrikaners - descendants of Dutch settlers who dominated during the apartheid era.

Speaking at the America Business Forum in Miami on Wednesday, Trump said he would not attend the upcoming G20 summit in Johannesburg, arguing that South Africa "shouldn't even be in the 'Gs' anymore because what's happened there is bad."

"I told them I'm not going. I'm not going to represent our country there," Trump added.

At Wednesday's forum, Trump also described Miami as a "haven for those fleeing communist tyranny in South Africa," adding that more people would soon arrive "fleeing communism in New York City," where Zohran Mamdani, a socialist politician and critic of Trump, was elected mayor this week.

Trump's rebuke apparently referred to immigrants from socialist nations in South America - a region he blasted during the same remarks - many of whom have settled in Florida.

The US leader regularly voices various grudges against nations in the Global South. He previously accused Mexico of "sending criminals" to America, criticized Brazil for prosecuting right-wing former President Jair Bolsonaro on charges of plotting a coup, and denounced Colombian President Gustavo Petro for allegedly being involved in the drug trade.

The G20 was founded in 1999 to accommodate non-Western nations that were gaining economic power. Supporters view it as more representative than the G7 group, which includes only the US and its allies.