The electricity supply is expected to be constrained in February and March, Eskom said on Monday.

"February and March are concerning for us. This due to budgetary constraints. Our financial director is looking at options in this regard," CEO Tshediso Matona told journalists in Johannesburg.

The power supply would depend on the availability of diesel during that period, he said.

The power utility used 140-million litres of diesel to produce power in November.

"We have had situations during this past week where the ordering of diesel was delayed due to budget constraints.

"Sometimes, in terms of logistics, things do not go smoothly between us, PetroSA and other suppliers," he said.