Schalk van Rensburg told a panel probing apartheid crimes that Roodeplaat Research Laboratories, a military front company, had produced poisons and given them to special forces agents to be used in killing anti-apartheid activists.
Mr Van Rensburg said the company had given them chocolates and cigarettes laced with anthrax, poisoned whiskey and orange juice and sugar containing salmonella.
He described himself as a political liberal who only realised the company's true nature after he joined. He said: "We had been told in no uncertain terms if we let the side down we are dead. If I stayed there, I could minimise a lot of [their] effort."
The commission is investigating covert military research programmes set up by Wouter Basson, who headed the army's Seventh Medical Battalion and operated through a sophisticated network of front companies.
Mr Van Rensburg said that he worked on a fertility project set up by Mr Basson to develop a "vaccine" against pregnancy. He suspected Mr Basson may have planned to use it on South Africa's majority black population. Mr Basson was forced to resign from the army in 1993. He is currently being investigated on charges of making and possessing the drugs ecstasy and mandrax.
Another scientist yesterday confessed to running a secret programme that made 912 kilograms of ecstasy with a street value of up to 1bn rand (pounds 122m).
Johan Koekemoer described working in 1992 for Delta Scientific, a Basson front company, and being asked to make the drug as part of a chemical warfare project. Mr Koekemoer said he suspected his superiors were dealing drugs on the side. He said: "From my personal point of view I don't think that ecstasy is an ideal compound to use as an incapacitant."Reuse content