He noted that R254-billion of the total expected investment over five years had already been approved by the utility's board, while contracts worth R83-billion had already been placed with suppliers. During the 2008/9 financial period alone, the utility would spend a record R46-billion.

"This is the key challenge for us, because as we spend, we need a confirmation of revenue . . . [otherwise] it is almost [as if] we are committing to suppliers with money we don't have," Maroga told a breakfast briefing organised by the SAS Institute and the Mail & Guardian on Thursday.

The statement came on the last day of public hearings, arranged by the National Energy Regulator of South Africa (Nersa), into Eskom's application for a massive 60% upward revision (from 14,2%) in its tariffs for 2008/9.

Nersa would make its final determination on June 18.

Most submissions have vehemently opposed the shock hike, arguing that the spike could not be absorbed by an economy already under severe inflationary strain, underpinned by rising food and fuel prices.

Alive to that opposition, as well as the proposal to ‘smooth' tariff increases over time, Maroga said that he would be "comfortable" with a "doubling" of prices over a five-year period, rather than the two-year timeframe proposed in its application to Nersa.

However, he continued to call for a regulatory framework that would give the utility the flexibility to respond to volatile contract and primary energy prices - in other words, a mechanism that enabled it to ‘pass through' rising diesel and coal prices, as the utility consumed more primary energy that initially envisaged on the back of a reserve margin that had fallen well below 10%.

Maroga also welcomed the R60-billion set aside by the National Treasury, which would help it in closing its funding gap but indicated that more might be needed.

All three of the rating agencies that track Eskom - Standard & Poor's, Moody's and Fitch - had placed Eskom on notice over recent months, asserting that they needed greater certainty on the nature and make-up of the funding plan to be employed in Eskom's build programme.

In fact, Moody's indicated recently that it could even consider downgrading Eskom by multiple notches, unless the ambiguity as to the mix of funding sources was resolved.

Eskom estimated that a single-notch downgrade by the international rating agencies of Eskom's credit worthiness could add between R3-million and R4-million to the cost of each R1-billion borrowed on the capital markets.