President Cyril Ramaphosa said on Friday South Africa will symbolically hand over the G20 presidency to an "empty chair" in the absence of US leadership at the summit next week, while stressing the need to repair trade ties with Washington.

US President Donald Trump said last week no government official would attend the Group of 20 summit on November 22-23 in South Africa because of what he said were "human rights abuses" - citing widely debunked assertions about white South Africans being "slaughtered" and chased off their land.

Trump has said that refugee admissions to the US this year will be focused largely on Afrikaners, who are mainly the descendants of Dutch settlers and make up the majority of South Africa's white population.

"I have said in the past, I don't want to hand over to an empty chair, but the empty chair will be there, (I will) probably symbolically hand over to that empty chair and then talk to President Trump...," Ramaphosa said, responding to questions from reporters in Soweto, where he was overseeing a clean-up for the summit.

South African officials are increasingly exasperated with Trump's claims that Afrikaners are victims of ethnic cleansing. They deny that anyone faces discrimination based on their race in the Black-majority country.

Ramaphosa said his priority was to maintain economic ties with one of its biggest trade partners.

"We export products to that country that in the end don't end up in the White House. They end up in the hands of consumers in the United States," he said.

"There could well be a view that we should not engage with the United States. (But) sometimes you have to talk to people who may not be very friendly ... to advance the interests of your own people".