At 0640 GMT, the rand traded at 12.7475 per dollar, 0.3 percent weaker than its close of 12.7100 overnight in New York.

Rand has posted net gains of nearly 3 percent in June after S&P Global Ratings and Fitch affirmed BB+ ratings following downgrades to subinvestment in April. Moody's decision due on Friday.

"The rand has continued to perform admirably, holding steady below the 13.0000 handle, some caution is advised as the move to the downside appears potentially stretched in the short term," said analyst at Nedbank Capital Reezwana Sumad.

Gross domestic product data for Q1 due at 0930 GMT. Reuters poll predicts 0.8 percent expansion following 0.3 percent contraction in previous quarter.

Government bonds were weaker, with the yield on benchmark paper due in 2026 up 3 basis points to 8.465 percent.

Stocks were set to open lower at 0700 GMT, with the JSE securities exchange's Top-40 futures index down 0.4 percent.