The strike in the metals and engineering sectors by over 200 000 Numsa members began on Tuesday, dealing a fresh blow to the economy after a five-month platinum mining stoppage that ended last week.
The Steel and Engineering Industries Federation of Southern Africa (Seifsa) said it had tabled wage hikes of up to 10%, up from 8% previously. The union wants increases of 12% to 15%, more than double the inflation rate.
"Regrettably, it would appear that we continue to be miles apart with the union," Seifsa chief executive Kaizer Nyatsumba said in a statement.
The offer was made during late-night talks on Thursday between the National Union of Metalworkers of South Africa and Seifsa. A Numsa spokesperson earlier declined to comment on the outcome of the talks.
There have been reports of violence and police on Thursday said officers had fired rubber bullets to disperse workers blocking the entrance to the construction site of Eskom's Medupi power station.
Economic damage is already being felt as the stoppage hits supplies of beverage cans and auto parts. The automotive sector might have to halt production if it continues beyond a week.
South Africa's biggest packaging group, Nampak [JSE:NPK], said about 40% of the 4 000 employees in its metals and rigid plastics division had failed to report for work.