Government bonds weakened as investors fretted about an uncertain outlook for Africa's largest economy, which has suffered three credit rating downgrades since September.

The yield on 28-year bonds maturing in 2026 closed 5 basis points higher at 7.235 percent, a two-week high, while a 24-year bond maturing in 2015 added 2 basis points to 5.35 percent.

The rand was at 8.89 to the dollar, a 1.12 percent drop from 8.7919 at Thursday's close.

It hit 8.9190 earlier in the session, its weakest since Dec. 3 according to Reuters data, making it the second-biggest loser on the day after the Polish zloty in a basket of 20 emerging market currencies watched by Reuters.

"There's continued negative sentiment on the rand - all these headlines that keep coming out about the mines," said Standard Bank trader Warrick Butler.

Harmony Gold Mining, South Africa's third-largest gold producer, said on Friday its Kusasalethu mine would remain closed until an agreement with trade unions was reached. The mine was shut last month on fears of violence and intimidation among workers.

Earlier this week, Anglo American Platinum (Amplats)  said it planned to mothball two mines in the country, sell another and cut 14,000 jobs as the world's largest producer of the precious metal struggles to stem losses.

"Today Fitch came out saying Amplats will certainly not be the last one looking at reassessing their business and mining interest in the country," Butler noted, saying this was keeping investors nervous.

The market is looking ahead to a monetary policy committee meeting next week, with traders almost fully pricing in a no-change stance on the benchmark repo rate, currently at a four-decade low of 5.0 percent.

Economists polled by Reuters on Friday also expected rates to stay unchanged after the Jan. 22-24 meeting, as the Reserve Bank balances sluggish growth with risks to inflation, including from a sharply weaker rand.