South Africa's electricity utility Eskom said on Thursday it would resume rotational power cuts from 9 am after a few days' reprieve and this would likely continue over the weekend.

Eskom, which supplies about 95 percent of the country's electricity, has been forced to intermittently apply load-shedding for months, suppressing demand to avoid overwhelming the grid in the face of frequent breakdowns in its generating units.

"We regret that Stage 2 rotational load-shedding will be implemented from 09:00 today until 06:00 on Saturday owing to the loss of 3 additional units overnight that has increased the shortage in capacity," it said on Thursday.

"There is a high probability that load-shedding will continue over the weekend, as there is a need to replenish reserves for the coming week."

The utility said it was currently utilising emergency reserves to supplement the shortage in capacity and reiterated that there was a possibility of increased load-shedding over the next 18 months as it conducted critical maintenance to restore its ageing plants to good health.

Eskom usually implements stage 2 load-shedding which requires throttling 2 000 megawatts of demand at any given time, but scaled this up to an unprecedented "stage 6" one day last year as pressure on the grid spiked.