South Africa's rand powered to a 5-week best as a contraction in the US manufacturing sector boosted bids for risk and emerging markets' currencies and fuelled bets the Federal Reserve would cut lending rates.

At 1645 GMT the rand was 0.74% firmer at 14.5620 per dollar compared to an opening level of 14.6430, climbing to its firmest level since Oct. 28 despite caution ahead of economic growth figures due in the next session.

On the bourse, stocks fell after investors were cautious ahead of the third quarter growth data expected to show Africa's most developed economy barely expanded. The benchmark JSE Top-40 Index was down 0.99% to 48,609 points while the broader All-Share Index fell 0.98% to 54,807.66 points.

Telecom firms MTN and Vodacom fell to the bottom of the blue-chip index after the Competition Commission ruled that they must lower data prices in the next two months or they could face prosecution. MTN declined 6.4% to 86.46 rand while Vodacom closed 5% lower at 115.07 rand.

Bonds firmed, with the yield on the benchmark paper due in 2026 down 1.5 basis points to 8.46%.

The poor manufacturing figures in the US, showing the sector contracted for a fourth straight month, pushed the greenback to a two-week low, giving room for risk currencies to rise.

Statistics SA publishes third quarter gross domestic figures on Tuesday at 0930 GMT.

A Reuters poll of economists and analysts sees quarter-on-quarter expansion at 0.1% from 3.1% previously, while year-on-year growth is forecast at only 0.4%.

The forecast for a weakening trend was bolstered by an November purchasing managers' index by Absa that showed business activity fell further into contraction territory. The index, a gauge of manufacturing activity in Africa's most industrialised economy, fell to 47.7 in November from 48.1 points in October, well below the 50-point mark that separates expansion from contraction.