JOHANNESBURG (Reuters) - South Africa's biggest union took the latest pay offer to its members for approval on Wednesday in a fresh effort to end a three-week strike that has halted output at several car factories. More than 200,000 metal and engineering workers led by the National Union of Metalworkers of South Africa (NUMSA) stopped work on July 2 demanding higher wages. The Steel and Engineering Industries Federation of South Africa (SEIFSA) on Tuesday "reluctantly" agreed to raise salaries by as much as 10 percent and gave unions until Friday to make up their minds. "The strike continues and has not been suspended. Our members, at the coal face of the strike, will make the final decision on whether to end the strike or not," NUMSA spokesman Castro Ngobese said in a statement. Ngobese said NUMSA would hold meetings in the next two days to solicit feedback from members about the offer, which SEIFSA has said would "inevitably lead to massive job losses". The industrial action, which has also disrupted work at construction sites of two vital power stations for Eskom, has dealt a further blow to the economy reeling from a five-month walkout in the platinum mines.