South African labor groups are close to agreeing on a wage deal that would end a four-week metalworkers’ strike that has threatened growth in the continent’s second-biggest economy, according to a union official.

The National Union of Metalworkers of South Africa, the country’s biggest labor organization, will probably announce that an agreement has been reached later today, said the official, who asked not to be identified as the decision hasn’t yet been made public.

The Steel and Engineering Industries Federation of Southern Africa, the country’s biggest group of employers, last week offered a 10 percent annual wage increase for three years to end the walkout of more than 220,000 workers. About 12,000 companies are affected by the strike, which is costing the industry about 300 million rand ($28.5 million) a day.

A call to the mobile phone of Castro Ngobese, Numsa’s spokesman, didn’t connect. He didn’t immediately respond to an e-mail seeking comment. Ollie Madlala, a spokeswoman for Seifsa, didn’t immediately respond to a message left on her office phone, an e-mail and a mobile-phone text message.