 South Africa's state-owned logistics firm Transnet says it is working to restore systems after the country's key port terminals suffered a major cyber attack last week. The security intrusion began on July 22, but has since continued, forcing Transnet to switch to manual systems. In a letter to its customers dated Monday, the company declared a force majeure, a clause, that prevents a party from fulfilling a contract because of external and unforeseen circumstances. It said it had experienced an act of cyber attack, security intrusion, and sabotage which resulted in the disruption of normal processes and functions.