South Africa's engineering and metal workers union has rejected a 10 percent pay-raise offer from employers, calling on its 220,000 striking members in the sector to intensify strike action.
Irvin Jim, general secretary of the National Union of Metalworkers in South Africa (NUMSA), the country's biggest trade union, said the workers would continue with indefinite strike action.
Should the employers continue with their reckless shenanigans and unreasonable demands, we might be left with no option but to call for targeted solidarity in all our sectors. This is seriously under consideration.
"We are making a very clear statement that the strike continues and we call on our members to intensify the strike," Jim said.
"Should the employers continue with their reckless shenanigans and unreasonable demands, we might be left with no option but to call for targeted solidarity in all our sectors. This is seriously under consideration."
Workers have already been off work for the past two weeks.
Employers have offered a 10 percent increase this year, 9.5 percent in 2015 and 9.0 percent the year after that, but NUMSA has dismissed the offer and threatened to drag in 100,000 NUMSA members in other sectors not on strike.
The strike, which began only a week after the end of industrial action in the platinum sector, has hit companies supplying components to the car industry, with General Motors closing its assembly plant in the southern city of Port Elizabeth.
It has also damaged wider investor sentiment in the country's economy, which is teetering on the brink of recession after a five-month strike in the platinum mining industry.
The Steel and Engineering Industries Federation of South Africa (SAIFSA) estimates that it is costing the South African economy about $30m a day.
The strike has also affected thousands of other companies across the manufacturing sector.