The company's credit rating was lifted to B, five levels into junk, from CCC+ by S&P on Friday, according to a statement. The credit assessor also changed the outlook to stable, saying the government's R254 billion financial support package will help cover Eskom's debt obligations for the current and the following two fiscal years.

"The extraordinary support from the South African government should reduce Eskom's refinancing and liquidity risk, subject to the group's compliance to the conditions set forth by the Eskom Debt Relief Act," analysts Manuel Vela Monserrate and Omega Collocott wrote.

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Still, the analysts expect Eskom's operating performance to remain under pressure due to weak operating efficiency. On Friday, South Africa was subjected to the deepest level of nationwide power cuts - or Stage 6 load shedding - in months as Eskom confronted generation capacity constraints and diesel shortages.

The long-term corporate family rating of Eskom was upgraded by Moody's Investors Service to B2 in September, five levels below investment grade. Fitch Ratings assigns Eskom the equivalent score.