Scheduled blackouts have burdened the continent's most industrialised country for several years, but got more frequent this year as power utility Eskom imposed many hours of electricity cuts daily.

"Eskom can confirm that the SANDF (South African National Defence Force) is being deployed," the energy firm said in confirmation. It "has received deployments at 4 sites this afternoon", the message added.

President Cyril Ramaphosa's spokesman Vincent Magwenya told AFP a minimum of 10 soldiers would be deployed in the initial phase at each station. Further deployments are in the pipeline.

The move was "in response to the growing threat of sabotage, theft, vandalism and corruption" at coal and diesel powered at power generating plants, he said.

South Africa has endured power shortages for the past 15 years, but the cuts reached new extremes this year.

They have cost the country hundreds of millions of dollars in lost output as well as disrupting commerce and industry.

Anger is growing among South Africans, who are now having to do deal with power cuts several times a day, sometimes totalling up to 11-and-half hours a day.

Earlier this week Eskom CEO Andre de Ruyter announced his resignation, citing crime and corruption as the main obstacles he faced in trying to turn around the troubled state-owned entity.