The outage occurred around 01:00 a.m. local time (00:00 GMT) "because of a sudden breakdown" in the Radès power plant, in the southern suburbs of Tunis, Steg said in a statement without giving details.
Electricity began to be restored from 04:00 a.m. in several neighborhoods of Tunis.
According to testimonies on social networks, this outage lasted more than four hours in certain areas.
This type of nationwide power outage rarely occurs in Tunisia.
This summer, due to a heat wave that exceeded 45 degrees Celsius, the authorities had to carry out scheduled load shedding, each time targeting a different region.
According to data from June 2023, the public company Steg supplies 99% of electricity in Tunisia, produced mainly from natural gas, with renewable energies (especially photovoltaics) representing only 2,5% of the total.
As the country is poor in hydrocarbons, natural gas comes mainly from Algeria thanks to samples at preferential rates made on the gas pipeline linking this country to Italy.
To complete this, Tunisia also imports natural gas from its Algerian neighbor and neighboring Libya.
Several regions of Tunisia have also experienced drinking water cuts in recent months, due to the drought which threatens water reserves.
The dams are currently filled to only 27% of their capacity and the government has implemented rationing until the end of September.