Seven South Africans were on board the Kenya Airways plane which crashed in Cameroon on Saturday morning, South Africa's Foreign Ministry spokesman Ronnie Mamoepa said.
After being informed by the airline that there were South Africans on the KQ507 flight, the ministry urged relatives or friends of these passengers to contact the ministry, the SAPA news agency reported.
The South Africans' names are not yet available.
"The South African government extends heartfelt condolences to the Kenyan and Cameroonian authorities as well as the South African families," Mamoepa was quoted as saying.
South Africa would also continue to support search and rescue efforts, he said.
The Nairobi-bound 737-800 aircraft disappeared after takeoff from Cameroon's port city of Douala, emitted a distress signal and is reported to have crashed off the coast of Cameroon, airline spokesman Glenn Lewington said.
Kenya Airways' Johannesburg office has set up an international passenger information center for information on flight KQ507 and public enquiries. A staff worker at the office told Xinhua that they are still waiting for the company to publish the full list of passengers.