The City of Johannebsurg said it expects systems to be back online over the weekend following a cyber attack.
The City tweeted: "The incident is currently being investigated by City of Joburg cyber security experts, who have taken immediate and appropriate action to reinforce security measures to mitigate any potential impacts.”
Several customer-facing systems, including the City's website, e-services and billing system were shut down as a precautionary measure.
The hackers were reportedly demanding the payment of 4.0 bitcoins by October 28 at 17:00 failing which they will upload all the data on to the internet.
Modingoane confirmed that the threat was detected on a user platform and said the City was investigating whether any customer information had been breached.