Ireland-based air carrier Ryanair said it would apply its language exam to any South African passport holder flying to Britain from another part of Europe on the carrier. The airline did not immediately respond to a query about why it would apply to those routes, given Britain says it is not a requirement.
"If they are unable to complete this questionnaire, they will be refused travel and issued with a full refund," a spokesman for the Irish airline said.
The UK High Commission in South Africa said on Twitter that the test was not a British government requirement to enter the United Kingdom.
Afrikaans is the third most spoken of 11 official languages in South Africa, used by 12% of the 58 million people in the country. It was considered the official language until the end of apartheid in 1994.
The language was born of Dutch settlement in South Africa in the 17th century, and has long been identified with racial classification and associated with the ideology of apartheid which was primarily enforced and propagated by the white minority National Party from 1948.
Its dominance under apartheid was seen as a symbol of inequality imposed on previous generations by restrictions on where people could live, work, go to school and own land.