South Africa's rand was slightly softer against the dollar at the start of Johannesburg trade on Wednesday, with labour unrest in the mining sector seen keeping it under pressure.

Government bonds also got off to a slightly weak start, with the yields on the three year and 14-year benchmarks each edging up half a basis point to 5.555 percent and 7.565 percent respectively.

By 0714 GMT the rand traded 0.34 percent weaker at 8.42582 to the greenback compared with Wednesday's close in New York.

The rand has been largely on the back foot since violence at Lonmin's Marikana mine left 44 people dead earlier this month, raising concerns about the viability of investing in the country.

“Our politics haven't been a factor for a while, it's certainly been on the back burner, but suddenly our politics are now on the radar,” said Jim Bryson, a currency trader at RMB.

“Certainly if we get any more bad news on the labour front, with the platinum mines, the foreigners really seem to be bothered about that,” he added.

The market was also eyeing Friday's meeting of central bankers at Jackson Hole in the U.S. for measures to revive the struggling global economy.

In the meantime, a sustained stay above the 8.37 mark could push the rand weaker towards 8.48/dollar, Bryson said. -Reuters