Nearly 20% of people arrested in Hong Kong in 2018 and 2019 for possession of drugs, smuggled the substance via OR Tambo International Airport, according to Hong Kong prison chaplain John Wotherspoon.
He said South Africa's ability to stop drug smugglers was not up to scratch.
Wotherspoon visited South Africa on Wednesday to raise awareness about the surge in drug trafficking via Africa's biggest and busiest airport.
In 2016, two people who boarded a plane at OR Tambo were arrested in Hong Kong, according to Hong Kong Customs and Excise.
In 2018, this number increased to nine people and in 2019 it peaked at 11.
"All those arrested boarded in Johannesburg and brought quantities of cocaine ranging from around 500g to as much 12kg, and all who admitted guilt reported the drugs were given to them by members of Nigerian syndicates operating in Johannesburg and Hong Kong," Wotherspoon said.
Nokwazi Memela is a former drug trafficker who was arrested in Iran for smuggling drugs from South Africa. She was given the death penalty but ultimately spent seven years in an Iranian prison.
"Life in prison was so very difficult for me," she said, adding she underwent a failed operation during this time and "stayed in prison for three days with an open stomach".
She could not report her situation, she said, because of the language barrier.
"I suffered in that prison until the South African government intervened," Memela said. "Iran was very difficult; I was treated like an animal. When you are black, they call you a baboon."
When she arrived back home, she added, she was not given any counselling and her case had not been investigated.
Wotherspoon has called for an improvement in airport security and the investigation of drug syndicates as well as for South Africa to negotiate prisoner transfer agreements for those who are locked up abroad.
"The prisoners say that getting through OR Tambo was easy, but Hong Kong airport by comparison has one of the most sophisticated detection systems in the world," he said.
Dr Marcel van der Watt, a former investigator with the Directorate for Priority Crime Investigation (the Hawks), said trafficking was a big problem in South Africa.
"Trafficking has been a major South African problem for well over a decade, with Nigerian syndicates boldly recruiting both South African and non-South African mules in various parts of the country.
"The authorities have consistently failed to respond whenever this issue is raised, and it is a massive indictment of this failure that a prison chaplain from Hong Kong has travelled here on his holiday to urge action," Van der Walt said.
While there are some reforms in the works to remedy the situation, the vulnerable are most at risk.
The Draft Protocol on Interstate Transfer of Foreign Prisoners, developed through the Southern African Development Community, aims to encourage agreements between member states regarding the repatriation of prisoners overseas.
"The drug trade is a lucrative one, and everyone demands their piece of the cake, including public servants. Largely naïve and vulnerable individuals are both the victims and casualties," Van der Walt said.