Pretoria - Thieves who broke into the closely guarded Denel complex in Kempton Park knew exactly what they wanted.

Only computer hard disks containing information of the Rooivalk attack helicopter were stolen in the burglary that shows signs of industrial espionage.

From evidence in the investigation thus far it appears the thieves knew exactly what they wanted and were not interested in computer equipment when they burgled the Denel aviation department.

The National Intelligence Agency (NIA) has joined police in the investigation, said NIA spokesperson Lorna Daniels on Wednesday.

Knew details about security

The joint probe was initiated as Denel's manufacturing plants are regarded as national key points.

Johan Holdt, who heads the Denel department, said the thieves were clearly in possession of information about the triple electrified fence surrounding the complex as well as its offices since they went directly to the offices from where they stole the computers.

Information stored on the hard-disks pertained mainly to the Rooivalk helicopter project, as well as Hawk fighter jet tail-section manufacturing details, which Denel manufactures on contract.

Holdt noted that the information mainly comprised details about helicopter production for the air force.

"We are almost certain that no blueprints were stolen. We keep those technical details elsewhere."

The thieves dug a tunnel under the electrified fence and then gained access to the building through a window three metres above the ground where the section for military aircraft is located.

Holdt said the window had not been not shut properly, but that it wasn't certain whether this had been done on purpose.

Power supply to the electrified fence is switched off at times and it appears the thieves were probably aware of these times.

The hard-disks of 25 desktop and laptop computers were stolen as well as an overhead projector.

Holding partnership talks

Closed-circuit security cameras were installed at strategic points after a spate of thefts in the workshops, which had put an end to these thefts. The cameras were mainly in the workshops and failed to record the weekend burglary.

Additional security measures have been put into place to prevent a repeat burglary.

The police said no arrests had been made.

The government and BAE Systems of Britain, manufacturer of Hawk training fighter jets, are holding talks to negotiate a strategic partnership between Denel and BAE Systems, which could result in partial privatisation of Denel.

Denel manufactures aircraft and other spare parts for a variety of commercial clients including Boeing and Rolls-Royce.

Denel's military aircraft section has been upgrading air force aircraft for several years. After the decision to acquire Hawk and Gripen fighter jets for the air force, the company became involved in manufacturing certain components of the two types of fighter jets locally.

With acknowledgements to Erika Gibson and Beeld.