A fire at a power sub-station near South Africa's Cape Town International Airport delayed flights on Tuesday as fire fighters battled to put out the blaze, an airport official said.

Flights were delayed by up to 45 minutes and some services at the airport were operating on back-up power supplies.

"We have back-up systems which are coming online with power. There are some baggage carousel which are working but we are also doing manual processing," airport spokeswoman Deirdre David told Reuters.

Neighbouring residential areas were also without power.

For much of this year, Eskom has had to resort to periodic power cuts to prevent the grid from collapsing, which has contributed to a 1.3 percent contraction in the economy in the second quarter.