The strike at Transnet, now in its fourth day, widened after a second union joined the stoppage, the latest public protest ahead of next month's soccer World Cup tournament, being held in Africa for the first time.
Nearly two-thirds of Transnet's 54,000-strong workforce joined the labour action, bringing the country's rail and port operations to a halt and threatening deliveries of metals, fruit and wine to customers in Europe and Asia.
Pradeep Maharaj, Transnet's HR Executive, said the container sector in ports and rail operations were hardest hit so far.
"However, we are continuing to meet our critical requirements in terms of exports through the ports and movement of bulk commodities," he told Reuters.
Transnet does not operate passenger services and is not a big transporter of coal to power plants, but a prolonged strike could affect imports, internal fuel supplies and exports of fresh fruit, grains, iron ore and coal.
"We have enough store capacity to take fruit until the weekend, but if it goes past the weekend, we start running into capacity problems," said Justin Chadwick, Chief Executive of the Citrus Growers Association.
He said the country's citrus industry, worth an annual 4.5 billion rand ($600 million) and second-largest producer after Spain, is currently storing oranges and grapefruits destined for Europe and Middle East in fridges, but space is limited.
The National Chamber of Milling said most of the country's maize was transported by road, but wheat imports could be hit.
The impact on coal and iron ore exports has been limited due to built-up stocks at ports, but the firms have said they would start feeling the crunch if the strike goes beyond this week.
Miners also said they were running out of space and would need to curtail production if they cannot ship products to ports.
South Africa is one of the world's biggest coal exporters, mainly to power stations in Europe and Asia.
Global miner Xstrata on Wednesday declared a force majeure, halting shipment of ferrochrome, a key ingredient in stainless steel, and chrome ore. Samancor, the world's 2nd-biggest producer, did the same, traders said.
Fifteen Percent
The United Transport and Allied Trade Union (Utatu) and the South African Transport and Allied Workers Union (Satawu) represent 85 percent of Transnet's workforce of 54,000 people.
Utatu said it would stick to its 15 percent pay rise demand when talks reopen, above the 11 percent offered by Transnet, fuelling criticism among analysts who say pay rises triple the inflation rate of 5.1 percent would hamper South Africa's recovery from its first recession in 17 years.
"This strike is a show of power ... we don't see them wanting to budge for less than 15 percent and that's outrageous," said Freddie Mitchell, an economist at Efficient Group.
Economists said it was too early to put a figure on losses from the strike, especially given built up stocks ahead of the strike, but said it could be in the millions of rand per day.
Central Bank Governor Gill Marcus said on Thursday high wage settlements not matched by productivity increases could pose a risk to the country's inflation outlook.
Utatu and Satawu met the mediator from the Commission for Conciliation, Mediation and Arbitration on Thursday, and are due to meet with the mediator and Transnet on Friday.
Transnet said it was willing to discuss options other than a further wage raise to end the strike, but stressed that going beyond 11 percent was unaffordable and unsustainable. (Reuters)
