Shell in South Africa said on Friday, Oct 5 it cannot 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, according to Reuters.

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.