The South African government has summoned the new US ambassador after he made what they called "undiplomatic" comments about an anti-apartheid chant.

Leo Brent Bozell III, who started in the role last month, caused offence by disagreeing with a legal ruling about the chant Kill The Boer. Some say the chant amounts to hate speech, although the Constitutional Court has ruled previously that it does not.

A formal protest was issued - known as a demarche - by the government, which said it took Bozell's comments "with a very dim view".

He issued a clarification on Wednesday and a representative of the foreign ministry later said the ambassador had expressed regret and apologised for the remarks.

On Tuesday, Bozell addressed a business meeting in the coastal town of Hermanus, presenting five issues he said South Africa needed to fix.

One was an argument over the chant. Bozell said he did not care what the courts said - comments that were taken as showing a lack of regard for the country's legal system.

He later retreated, saying he was ''willing to work with South Africa constructively'' and that ''the US government respects the independence of South Africa's judiciary''.

At a press conference on Wednesday, the South African government announced they had called the US ambassador to Pretoria, to explain his recent undiplomatic remarks.

Ronald Lamola added that the relationship between South Africa and the US was not one-sided. ''South African companies maintain a significant investment in the United States," Lamola said.

"Mr Bozell expressed his regrets that these comments detracted from any impression that he wanted to work with us constructively," Zane Dangor, the director-general of the Department of International Relations and Cooperation, said later.

Relations between the US and South Africa have deteriorated since US President Donald Trump took office last year, with the two sides clashing over trade, diplomacy and South Africa's strategic partnerships.

Trump has been openly critical of South Africa's President Cyril Ramaphosa's government, accusing it of failing to protect the country's white minority and criticising its land reform plans.

The South African government, meanwhile, has criticised the US decision to prioritise refugee applications from white Afrikaners, saying claims of a white genocide have been widely discredited and lack reliable evidence.

Tensions deepened last year when the US imposed the highest tariffs of any African country on South Africa.