South Africa port operations halted and workers reportedly put on leave after major cyberattack

Transnet, a state-owned South African rail, port and pipeline company, appears to be in crisis mode after a cyberattack hit the company five days ago.

The logistics firm has been forced to halt operations at container terminals in Durban, Ngqura, Port Elizabeth and Cape Town, Bloomberg reported Tuesday, citing a note that Transnet sent to customers.

"Transnet, including Transnet Port Terminals, experienced an act of cyberattack, security intrusion and sabotage, which resulted in the disruption of TPT normal processes and functions or the destruction or damage of equipment or information," the note reportedly reads.

"Investigators are currently determining the exact source of the cause of compromise and extent of the ICT data security breach or sabotage," it continues.

Transnet did not immediately respond to a CNBC request for comment. Its website was still inaccessible on Tuesday morning and showing an error message.

The Johannesburg-headquartered company, founded in 1991, said Thursday that it was experiencing disruption on its IT network. On Friday, it said it had identified and isolated the source of the disruption.

But the technical issues seem to be persisting. In the customer note, Transnet reportedly declared "force majeure," which is when unforeseeable circumstances prevent a company from fulfilling a contract.

Transnet's port in Durban handles over 60% of South Africa's container traffic.

The company is taking "all available and reasonable mitigation measures" to limit the impact from the disruption, according to Bloomberg.

Last Friday, the boss of South Africa's Road Freight Association said in a statement that he was "dismayed and gravely concerned" about the cyberattack.

Gavin Kelly, RFA's CEO, said the attack has resulted in "massive delays and unreliability of the movement of goods across all modes of transport," adding that road freight is bearing the brunt of the impact.

"The gates to ports are closed which means no trucks are moving in either direction," he said. "This has immediate effect: the queues will get a lot longer, deliveries will be delayed and congestion will increase."

The disruption puts Africa's most industrialized economy in further jeopardy. South Africa is trying to recover after deadly riots following the imprisonment of former President Jacob Zuma. 

Transnet has asked some of its employees who were not involved in running operations to take leave until the issues have been fixed, Reuters reported Tuesday, citing two sources familiar with the matter.