Two people have appeared in a South African court, charged with illegal trafficking of human organs.
They are accused of being part of an international syndicate which buys body parts from poor people in Brazil and Israel for use in South Africa.
The ring allegedly supplies kidneys to surgeons who perform illegal transplants at South African hospitals.
Police say the syndicate offers donors about $10,000 per kidney, which are then sold for up to $120,000.
In many Western countries, there are long waiting lists for human organs such as kidneys, livers and bone marrow.
South Africa hospitals have a worldwide reputation for their expertise in the field of organ transplants.
Nine Brazilians and two Israelis have also reportedly been arrested in north-eastern Brazil in connection with the organ ring.
"In all, they managed to talk 30 men into selling one of their kidneys," said Wilson Salles Damazio, head of the Federal Police branch in Pernambuco state.
He said that those who passed medical tests were sent to South Africa, where their organs were removed, before flying back home.
South African police have interviewed several Brazilians and Israelis staying in Durban, allegedly brought there to sell their organs.
Israeli citizen Agania Robel, who is 41, was reportedly arrested after undergoing a kidney transplant.
According to The Star newspaper, it is alleged that he bought the kidney through the syndicate.
Mr Robel was granted bail of 5,000 rand ($800) by the Durban magistrate.
Sushan Meir, 49, a South African of Israeli origin, was granted bail of 15,000 rand ($2,400) for allegedly being involved in a kidney-transplant transaction.
Police are expected to turn their attention next to medical workers in two Durban hospitals.
St Augustine's hospital has confirmed that it is helping police with their inquiries.
The investigating officer, Captain Helberg, has said that the investigation into the matter does not involve the hospital being party to any illegal transactions.
Investigators believe the illegal trade has been going on for more than a year and more arrests are expected.
"We are looking at members across the globe. We have had successes in Brazil, Israel and South Africa, but we suspect it is much wider," said Police spokesperson Mary Martins-Engelbrecht.