Children as young as eight are peddling heroin in schools in Mpumalanga coal-mining towns eMalahleni and Middelburg.
A local eMalahleni rehab clinic has treated 48 children for heroin addiction in the past year, and claims the problem has exploded.
Tomorrow, a report by the Global Initiative Against Transnational Organised Crime and Interpol is due to be released, showing how lax and corrupt police and customs officials have allowed international drug traffickers to swarm into South Africa.
The researchers say Middelburg has been particularly affected because it is a popular stop for truckers ferrying heroin along the N4 from Mozambique ports to Johannesburg.
INTERNATIONAL TRANSIT HUB
The report, which the Sunday Times has seen, says South Africa has become a major international transit hub for heroin produced in Afghanistan and Pakistan. This is because narcotics smugglers have shifted their attention from traditional European smuggling routes, due to increased security linked to terrorism and illegal immigration, to countries along Africa's east and southern coast.
The report also names Gauteng's City Deep container depot as a heroin smuggler's haven, and says 75,000 South Africans inject heroin daily, the highest number in Africa.
City Deep annually handles more than 400,000 shipping containers, which are used to transport goods across the country, to neighbouring countries and overseas.The report says the "leakage" trade - smugglers selling some of the drug consignment to local markets - has devastated towns like eMalahleni.
It says the "dramatic rise" in heroin use over the past four years has been "obscured, in public debate, mostly because it is being marketed as nyaope and unga, sometimes referred to as woonga". 
Zelda Makhubele, eMalahleni director at the South African National Council on Alcoholism and Drug Dependence, said the heroin problem in the town had rocketed.
"Those coming to us for help, especially for heroin abuse, are getting younger and younger. It's children who are still in primary school. The youngest we have is eight. He was sharing and dealing nyaope with friends at school."
She said the boy got hooked after stealing his grandmother and uncle's supply.
Makhubele said that in May, their Sanca branch helped an 11-year-old boy who was selling heroin at school. "The mother and her son were placed in police protection. The dealers were looking for the mother because she destroyed 10kg of nyaope which they gave her son to sell in school. They wanted her to pay for what she had destroyed."She said that in the 2016-17 financial year Sanca helped two children. "In the 2017-18 financial year it was 48. Over these two financial years the number of people addicted to heroin who we have helped has risen from 376 to 657."
Elize Banks, founder of Xtreme Buddies rehab in eMalahleni, said the town's children were being "decimated". "The youngest we have helped is nine. Last week we helped a mother bury her 15-year-old son."
The report says heroin syndicates hook people with free "starter packs".
"Smuggling heroin in containers often takes little more than bribing a forklift driver, clearing agent or customs officials ... Corruption at City Deep is endemic."
It describes Pretoria and Durban as the country's heroin repackaging hubs, Johannesburg as the heroin "warehousing and transhipment facility" and Cape Town as the distribution hub for the European market.
MULTIFACETED RESPONSE
The report's co-author, Simone Haysom, said that to deal with the heroin problem there needed to be a multifaceted response at a regional level which looked at policy development that would involve the region's police forces, governments and public health sectors, as well as the establishment of a maritime coastal enforcement network to stop seaborne smugglers.
eMalahleni spokesman Kingdom Mabuza said the municipality had recently relaunched a local drug action committee. "The committee is working with various role players to stamp out this scourge."
Transnet spokeswoman Nompumelelo Kunene said ports and terminals had security systems in place to ensure the safety of "our customers' goods". It was not a Transnet mandate to ensure containers were searched, but that of law enforcement.SARS spokesman Sicelo Mkosi said customs officials intervened at various stages of the import-export supply chain based on the risk ascribed to a consignment. This included post-clearance inspections.
"SARS uses risk-based targeting to monitor and scrutinise all electronic declarations against a set of stringent rules. The inspection includes that of documents, physical inspections, dog inspections and scanners to ensure optimal coverage of goods entering and leaving the country."
To stamp out corruption, all SARS officials were subjected to strict vetting procedures upon recruitment, he said.
Police spokesman Brigadier Vish Naidoo referred questions to the Hawks, which did not respond.
Haysom said the report's findings had been submitted to the police, and various South African government departments would be briefed on the report this month...