South Africa apologized on Thursday for the mass deportation of 125 Nigerians after a yellow fever scare.

The incident, in which South African authorities turned away Nigerians they believed forged vaccination cards, became the source of serious diplomatic tensions between South Africa and Nigeria, sub-Saharan Africa's two largest economies. One of those deported was a Nigerian senator, according to South Africa's Vanguard newspaper.

“We apologize for this unfortunate incident and we hope this matter will not in any way affect our bilateral relations,” said Deputy Foreign Minister Ibrahim Ibrahim from Pretoria.

“We’ve put into place certain mechanisms to ensure this doesn’t happen again, and we believe that this matter is closed,” he added.

“We are in contact with the embassy in Nigeria, to see that there are no longer problems, and that any difficulties over vaccination certificates are dealt with before a visa is issued.”

Since the initial incident, Nigeria has deported dozens of South Africans and threatened to take action against South African companies.

Nigeria's minister of health, Onyebuchi Chukwu, also took subtle jabs at South Africa during a press conference in Abuja earlier this week, where he proclaimed that there have been no confirmed cases of Yellow Fever, a potentially deadly mosquito-carried virus, in Nigeria since 1995.

“What you see playing out is what we call xenophobia by South Africans against all Africans -- not just Nigerians -- including even those from their neighboring countries,” Nigerian Foreign Minister Olugbenga Ashiru said on Tuesday.

Vaccination cards are required for travel within the African continent.