South Africa has tendered “unreserved apology” to Nigeria over a mass deportation of its citizens, saying officials at Johannesburg’s main airport did not properly check their health certificates, the News Agency of Nigeria reports.

At a news conference in Pretoria Thursday, Deputy Foreign Minister, Ibrahim Ibrahim said: “We wish to humbly apologize to them, and we have.”

Two diplomats from the Nigerian High Commission accompanied Mr. Ibrahim to the news conference, but refused to comment beyond a joint statement that says the tit-for-tat deportations between the two countries in the past days should not affect their relations, the Associated Press said.

On March 2, South Africa deported 125 Nigerians who, according to airport health authorities, carried fraudulent yellow fever cards. Since then, authorities in Lagos have deported South Africans, raising similar health concerns.

Following the dispute with Nigeria, South Africa has also now agreed to vaccinate at airport, travellers without yellow cards instead of deporting them.

Mr. Ibrahim said South African airport authorities did not properly check to determine whether the cards were authentic. He said South Africa was considering reopening a health clinic at the airport to ensure such deportations are not repeated.

South Africa and Nigeria are allies, but also sometimes rivals for influence in Africa.

Nigeria Foreign Minister, Olugbenga Ashiru, speaking to the National Assembly Tuesday, linked the deportations to what he called the “xenophobia” faced by Nigerian immigrants living in South Africa who fear police could arrest them without cause.

Mr. Ibrahim rejected Mr. Ashiru’s charge.

“We are not a xenophobic country,” the South African minister said Thursday.

But in 2008, South Africa saw a wave of violence against foreigners from elsewhere in Africa that left scores dead.