Johannesburg - Transnet has not received any formal notification of the planned strike from workers' unions as required by labour legislation, it said on Friday.
"We are hopeful that through ongoing discussions we can find each other and resolve this issue," said spokesman John Dludlu.
"We are continuing with our contingency plans to ensure minimal impact on our operations and we will endeavour to meet as far as it is possible to meet our customers' requirements should the industrial action materialise."
South Africa's transport system was expected to be brought to a standstill from May 10 as 50 000 Transnet workers planned to strike over a wage dispute.
"This will be the biggest strike in the history of South Africa," said Chris de Vos, general secretary of the United Transport and Allied Trade Union (Utatu) at a press conference in Johannesburg on Friday.
"It will make all other strikes look like kindergarten parties."
Utatu will join the SA Transport and Allied Workers' Union (Satawu) in the national strike against parastatal Transnet. It was expected to affect all freight rail, shipping and harbours, and fuel and coal line services.
While Metrorail employees were not expected to join the strike yet, they were in a similar wage dispute, through the same unions, and it was possible that they could still join. SA Airways would not be affected.
"It will affect everything," said Satawu general secretary Zenzo Mahlangu.
"Freight, pipelines, ships. The delivery of goods incoming and outgoing from our ports and the coal lines coming in and out."
He said if the strike was prolonged, it might lead to a "serious" fuel problem in the country.
The unions said they were united in their cause of getting a 15% wage increase for their members across the board. Transnet was only offering increases of eight percent.
Satawu's Jane Barret said the strike would be indefinite, until an agreement had been reached, but said it was unlikely that the strike would last until the Soccer World Cup.
"It is unlikely that we won't get a settlement in five weeks," she said.
Mahlangu said the strike could still be called off, should Transnet come up with a "substantial" settlement.
"We would like to apologise in advance for any inconvenience caused," he said.
"Strike action is not a tactic we like to use, but we use it as a last resort. Our members are eager to strike. They would go on strike today if they were allowed."
Mahlangu said the Transnet employees felt cheated and their morale was the lowest it had been in 40 years.
Other than the wage issues, the unions also wanted contract workers employed on a permanent basis, and a guarantee that no retrenchments would be made for the next year, among other demands.
Eighty-seven percent of Transnet's workforce is unionised.
- Sapa