At 0850 GMT the rand was 0.4pc weaker at 13.9375 to the dollar, having opened the session 13.8950.

Eskom, which supplies more than 90pc of South Africa's power but had to implement power cuts earlier this year, is grappling with high debt and has needed cash injections to stay afloat.

Finance Minister Tito Mboweni presented an appropriation bill to parliament on Tuesday to give Eskom the extra cash, but warned at the same time of lower-than-expected tax revenues and higher public debt levels.

In a worst-case scenario, Moody's said it expected South Africa's fiscal deficit could widen to 5.7pc of gross domestic product in 2019, up from current projections of 5.2pc.

Bonds also slipped, with the yield on the benchmark 10-year government issue up 4 basis points to 8.13pc.