The rand was at 8.5750 to the greenback by 0644 GMT, down 0.7 percent from Thursday's close at 8.5160.

It briefly touched an 18-week low of 8.5918, taking it closer to a three-year low of 8.71 touched on June 1.

"We are being driven by continued bad news on the labour front. Any good news would be helpful," RMB trader Jim Bryson said.

"We have had quite a quick run up (rand weakening) from last Friday and we're most probably needing to set a new high today, a break of 8.55, otherwise we might start to consolidate a little bit, get into something like an 8.40 - 8.55 range.

"But certainly above 8.55 look for the weakness to continue to something like 8.60 and 8.70 most probably."

South Africa's investment image has taken a knock and local assets have been battered due to mostly illegal strikes that hit platinum mines in August and spread to the manufacturing sector for the first time this week.

Government bonds fell alongside the rand on Friday, and the yield on the three-year benchmark added two basis points to 5.34 percent while that for the 14-year issue was up five basis points at 7.575 percent.