Load shedding will move from stage 3 to stage 4 by midday on Saturday, Eskom announced.
"Due to the loss of an additional 900 MW from the Mozambique imports, load-shedding will move up to stage 4 from 12 noon," the power utility said in a statement.
This followed earlier confirmation that Eskom had moved from stage 2 to stage 3 at 10am.
“Eskom regrets that rotational load-shedding has moved up to stage 3 from 10am, due to the loss of additional power station units, which includes a reduction in imports from Mozambique,” Eskom said.
Earlier on Saturday Eskom announced it would be implementing stage 2 load-shedding from 8am 11pm due to a shortage of capacity and a loss of additional generating units.
However just after 10am the power utility alerted consumers via Twitter that due to a loss of additional capacity, including imports from Mozambique, load shedding would be kicked up to stage 3.
"The situation remains tight and volatile and we may have to implement further load shedding should the situation deteriorate. Depending on how quickly we can restore power, this may impact the prognosis for tomorrow and next week," the power utility warned.
Eskom said stage 3 calls for 3,000 megawatts (MW) to be rationally load-shed at a given period.
“Load-shedding is conducted rationally as a measure of last resort to protect the power system from a total collapse or blackout,” the power utility said.
On Thursday, Eskom said it would cut electricity after a unit at its faulty Kusile power station tripped, adding to a shortfall of generating capacity.
Eskom, which supplies more than 90 percent of the country's power, has suffered a series of unplanned breakdowns at its creaking coal-fired power station fleet which limit its ability to power the country.
Kusile is one of two new multi-billion rand power stations which have suffered massive cost overruns and technical problems.
On Thursday, Eskom said in a statement that it planned to cut 1,000MW on a rotational basis countrywide from 11am to 11pm, a month after implementing some of the worst power cuts in several years.
Eskom's problems are a major challenge for President Cyril Ramaphosa as they have shaken investor confidence and threatened to stymie efforts to rekindle growth before a parliamentary election in May.
Ramaphosa's government has promised to inject R23-billion a year over the next three years to shore up Eskom's balance sheet and appointed a team of experts to come up with a plan to improve the firm's operational performance.