South Africa on Wednesday said its authorities had arrested and would deport seven Kenyan nationals illegally working on processing refugee applications for the US government.

President Donald Trump's administration aims to bring thousands of white South Africans to the United States under a resettlement programme it started this year, on the basis of claims that they are victims of racial persecution. South Africa's government strongly denies this.

According to the US embassy website, processing for the refugee programme in South Africa is being done by Amerikaners, a group led by white South Africans, and RSC Africa, a Kenya-based refugee support centre operated by Church World Service. 

The Kenyans had entered South Africa on tourist visas and illegally taken up work at a processing centre, despite the fact that earlier visa applications for Kenyan nationals to do this work had been denied, South Africa's Ministry of Home Affairs said in a statement.

 The seven were arrested during an operation on Tuesday and issued with deportation orders, it said.

CNN reported on Tuesday that two US government employees were also briefly held, then released. The South African statement said no US officials were arrested.

The incident is likely to worsen already bad relations between Washington and Pretoria. During his second term, Trump has repeatedly made false claims about South Africa's treatment of its white minority, and used this as a justification for cutting aid and excluding South Africa from G20 meetings. 

"The presence of foreign officials apparently coordinating with undocumented workers naturally raises serious questions about intent and diplomatic protocol," the South African statement said. 

"The Department of International Relations and Cooperation has initiated formal diplomatic engagements with both the United States and Kenya to resolve this matter."

The US State Department did not immediately respond to a request for comment. RSC Africa could not be immediately reached for comment.

A State Department spokesperson was quoted by CNN as saying that "interfering in our refugee operations is unacceptable" and that the US government would be seeking immediate clarification from the South African government. 

A spokesperson for Kenya's foreign ministry said she was not aware of the incident but would look into it.