South Africa's steel and engineering employers group said on Tuesday it had withdrawn a "final" wage offer made to the striking NUMSA union to end a two-week industrial action.

The strike by 220,000 NUMSA members has affected production at car makers such as Ford, Toyota and General Motors because of supply chain problems related to the stoppage.

"The final offer made last week – which was intended to end the strike and to see employees back at work this week – failed to accomplish its goal and has since been withdrawn," Kaizer Nyatsumba, chief executive of the Steel and Engineering Industries Federation of Southern Africa, said in a statement.

NUMSA is seeking 12-15 percent annual increases. Employers had offered a 10 percent increase this year, 9.5 percent in 2015 and 9.0 percent the year after that.

"The employers have withdrawn their offer but they've made an undertaking that they're going to their chamber and they'll come back to us before the end of the week," NUMSA spokesman Castro Ngobese said.

The NUMSA leadership was meeting on Tuesday to discuss plans to widen the strike, he added.

The strike follows on the heels of a five-month strike in the platinum sector that stunted economic growth and export earnings and damaged wider investor sentiment in Africa's most advanced economy.