A ndre de Ruyter had been drinking his morning coffee hours after resigning as chief executive of South Africa's troubled national power generator, when he suddenly began to feel violently ill. 

The normally healthy 6ft 4in businessman was soon dizzy, and shaking uncontrollably.

"I was unstable and very confused," Mr de Ruyter told The Telegraph. "I was not walking properly and gasping for air."

Bodyguards rushed him out of Eskom's Johannesburg headquarters last month, to a nearby clinic for emergency treatment and tests.

The results of those tests have since shocked South Africa and again turned the spotlight on the country's struggle with ruthless and frequently murderous corruption.

Doctors told the 54-year-old his blood showed high levels of cyanide in what he believes was an attempted assassination because of his efforts to turn around and clean up Africa's biggest corporation after years of systematic looting.

The alleged hit might appear more reminiscent of the mafia chaos in 1990s post-Soviet Russia.

Days after Mr de Ruyter first released details of his poisoning, an apparent assassination attempt struck the vice chancellor of a major university, who had also been trying to root out corruption.