By Marlene Burger

A highly volatile chemical substance on board the Helderberg, the SAA aircraft that plunged into the sea off Mauritius in 1987, was a vital component of Project Coast, the apartheid government's chemical and biological warfare programme.

The significance of an apparently negligible amount of the extremely dangerous substance was recognised by a former employee at Delta G Scientific, a military front company, during the investigation that has led to the current trial of Project Coast chief Wouter Basson.

The Basson investigation has turned up a Helderberg weigh bill which records the presence of 300g of the substance.

However, efforts to make a direct link between Project Coast and the 300g of activated carbon shipped from Tokyo to Johannesburg-based chemical importer Mikem Africa have been frustrated by the extraordinary secrecy surrounding the chemical and biological warfare project and the destruction of documents.

If the activated carbon did cause the fire on the doomed aircraft, the legal repercussion would prevent anyone from now admitting the deadly cargo was on its way to Project Coast.

But the Helderberg crash, which claimed the lives of all 159 people aboard the Boeing 747 Combi, came at a time when a South African company was preparing to manufacture 45 000 sets of clothing designed to protect troops against nuclear, biological and chemical (NBC) attack.

The protective inner lining of the so-called NBC suits contains activated carbon.

During cross-examination of Niel Knobel, the former SADF surgeon-general, last November, Basson's defence counsel, Jaap Cilliers, said the activated carbon was so finely ground that it "appeared almost liquid" when poured.

Even after insertion in the suits, Cilliers claimed, the chemical molecules remained in perpetual motion, and spontaneous combustion could result.

According to Cilliers, this had caused a secret SADF depot to burn to the ground, destroying thousands of NBC suits.

Ironically, Cilliers also told Knobel that Basson - who was never involved in the official investigation - believed a chemical fire had been the cause of the plane crash.

The former Delta G employee, who does not wish to be named, said this week that an activated carbon fire could smoulder "for days - you might think you had it under control, but it would flare up again, no matter what you tried to extinguish it with".

There has long been speculation that there were two fires on board the Helderberg on the night of November 28 1987, the first shortly after the aircraft took off from Taipei, and another as it prepared to land at the Mauritius airport, by which time all fire extinguishers on board would have been empty.

The official Margo enquiry into the crash pinpointed the source of the fatal fire as the cargo pallet in the front right-hand corner of the upper hold. The activated carbon is believed to have been on that pallet.

Knobel, who was Basson's immediate superior on Project Coast, testified that he and other SADF generals serving on the Controlling Management Committee "did not want to know" details of what chemicals and technology Basson acquired, nor where or how he did so.

Because of the extreme sensitivity of chemical and biological programmes, Basson was given extraordinary leeway, as the SADF high command believed "the end justifies the means".

There has been speculation over the years that the cargo which caused the Helderberg fire originated in the United States and was shipped to Taipei via a circuitous route, including Tokyo, to disguise this fact.

Knobel is on record as saying Project Coast's "achievements" would never have been possible without the clandestine support of foreign intelligence agencies, such as the CIA and MI5, but has stopped short of indicating whether such assistance was officially sanctioned by the American and British authorities.

One of the few restrictions placed on Basson, according to Knobel, was that he was not to use commercial airlines to transport chemicals for Project Coast, because of the potential hazards.

However, several senior South African Airways pilots have admitted in the past few years that they ferried arms components and explosives clandestinely on passenger flights in sanctions-busting exercises.

International airline regulations prohibit the transport of more than 100g of activated carbon on any flight. The substance must be packed in a steel container and the total weight may not exceed 500g. The 300g of activated carbon on the Helderberg thus exceeded the safety limit by 200g.

According to scientists, activated carbon is "highly and spontaneously combustible" when exposed to heat and becomes explosive when combined with acetone. The Helderberg cargo also included a consignment of beauty products, many of which contain acetone.

Mixed with liquid oxygen, activated carbon becomes a powerful bomb "which leaves no trace", scientists say.

In his testimony against Basson last year, Knobel said that in 1986 a company called Technotek was instructed to launch research into the "special material" needed for production of NBC suits.

In February 1987, just nine months before the Helderberg crash, Technotek was given a multi-million rand contract to deliver 45 000 NBC suits to the SADF over the next three years.

The company was owned by Charles van Remoortere, a Belgian businessman based in Pretoria, whose father served as deputy to the US's General Alexander Haig while he was commander of the North Atlantic Treaty Organisation in the 1970s.

The NBC suits for the SADF were manufactured on sub-contract by National Tents & Sails.

Among the 61 charges of drug dealing, fraud and murder that Basson is facing are three related to the unauthorised sale of more than 30 000 NBC suits from SADF stores to a Belgian company, Seyntex, during the 1991 Gulf war.

Basson allegedly used the R10-million proceeds of the deal for personal gain. The suits are believed to have been supplied to allied forces in the Persian Gulf.