(Bloomberg) --

AngloGold Ashanti Ltd., temporarily halted work at its Mponeng gold mine in South Africa after more than 164 workers tested positive for Covid-19.

The world’s third-largest gold miner detected a cluster of infections after a mass testing campaign, and the majority of confirmed cases were asymptomatic, said Chris Nthite, a spokesman for the company. AngloGold conducted 650 tests since Thursday, he added. Mponeng, the last of AngloGold’s South African assets, employs about 5,000 workers.

“As a precautionary step, operations at Mponeng Mine -– which were running at 50% capacity -– have been temporarily halted on a voluntary basis to complete contact tracing and to again deep clean and sanitize the workplace and key infrastructure,” Nthite said.

AngloGold is in the process of selling Mponeng, the world’s deepest mine, to Harmony Gold Mining Co., a deal that’s expected to close at end of June. The producer has suspended its guidance for full-year output of 3.05 million to 3.3 million ounces of gold amid the coronavirus pandemic.

More on South African mining challenges

Workers in South Africa’s mines, which employ more than 450,000 people, are particularly vulnerable as they toil in cramped shafts that can reach more than two miles underground, before returning to overcrowded hostels and shanty towns.

©2020 Bloomberg L.P.