South Africa's government has summoned the United States (US) ambassador, Leo Brent Bozell III, over what it described as "undiplomatic remarks."

The envoy sparked controversy on Tuesday when he said the South African liberation chant "Kill the Boer" amounted to hate speech, despite local courts ruling that it does not.

Foreign Minister Ronald Lamola said the ambassador had been called in to explain the remarks.

"In this regard, we've called in the ambassador to explain his undiplomatic remarks, in his engagements and visits to the Apartheid Museum, District Six and other similar South African landmarks," Lamola said in a statement.

Lamola added that Bozell acknowledged South Africa's history requires redress and had expressed a willingness to work constructively with the government.

Another senior foreign affairs official, Zane Dangor, said Leo Brent Bozell III had apologized and expressed regret over his remarks.

Diplomatic relations between South Africa and the US have deteriorated during Donald Trump's second term in office, with the two sides clashing over trade and diplomacy.