The National Union of Mineworkers, which also represents construction workers, said a national sympathy strike would start in a week if workers' demands in Durban weren't met.
Hundreds of workers at Moses Mabhida struck a week ago over poor pay conditions according to Reuters.
"We are meeting with the city manager tomorrow, when he will brief us regarding the development. Any dispute must be resolved in the quickest possible time," said Danny Jordaan, chief executive officer for the 2010 local organizing committee.
The union is demanding a minimum wage of $1.62 an hour, project bonuses of $221.46 a month for each worker, and safety improvements.