Shell in South Africa said on Friday it can not guarantee honoring contracts to deliver fuel around Johannesburg, the first sign of a two-week strike by more than 20,000 truck drivers hitting Africa's biggest economy.
Weeks of wildcat strikes have rocked the country, pushing the rand to near three-year lows against the dollar, and raising questions about the ability of the ruling African National Congress to manage the crisis.
"There is fuel available across the country, so the issue is not fuel supply, but the challenge is delivering it safely to our retail sites," Shell said after invoking a "force majeure" clause that allows it to break contracts due to situations beyond its control.
Other petrol companies are holding their breath but have not yet followed Shell's move.
The SATAWU transport union said it was pushing for rail and ports workers to join the strike next week.
The country's mining sector, which accounts for about 6 percent of GDP, has been particularly hard hit by the labor unrest, with a wave of walk-outs by platinum, gold and iron ore workers.
Near the "platinum belt" city of Rustenburg, 120 km (70 miles) northwest of Johannesburg, workers said a miner was killed by a rubber bullet fired by police overnight, pushing the death toll from weeks of labor strife to 48.
"He was shot here by the police," Mbubhu Lolo, a striker from Anglo American Platinum, told Reuters, pointing to his midriff.
Police would not confirm the cause of the death. They are maintaining a strong presence in the area after using teargas and water cannon to disperse protesters who were on Thursday hurling stones.
Protesters barricaded streets with rocks and burning tires on Friday close to a mine belonging to top producer Anglo American Platinum (Amplats).
The ground near the hill where strikers have been gathering was strewn with empty teargas canisters and dozens of empty rubber-bullet shell casings that residents said were used by police to break up the crowd on Thursday.
The strikes also spread to the manufacturing sector for the first time this week, with workers at Toyota's Durban car plant downing tools on Monday to demand higher pay. The strike was resolved on Thursday, with unions saying workers had received a 5.4 percent pay hike.
"As far as I know, the guys have been pitching up for work and production has restarted," Toyota SA spokesman Leo Kok said.
Coal output in one of the world's biggest suppliers was still largely unaffected. Should the strikes spread to coal it could hit supplies to power utility Eskom, already struggling to prevent a repeat of a 2008 crisis when the grid nearly collapsed. Some 85 percent of the country's electricity is generated by coal-fired plants.
(Writing by Ed Cropley and Jon Herskovitz; Editing by Will Waterman)