Harmony Gold mine Kusasalethu in Carletonville. 
Photo: Supplied

Johannesburg - Workers at Harmony Gold's Kusasalethu mine west of Johannesburg have returned to work, ending an illegal strike that started more than two weeks ago, the company said on Thursday.

Kusasalethu, which employs about 4,500 workers, has been a flash point for labour violence and strikes in recent years, threatening the viability of the mine and underlining the social risks of mining in South Africa.

"Unprotected industrial action affects the mine's viability, its employees and their families," Harmony CEO Peter Steenkamp said in a statement.

Workers downed tools on March 23 after the Association of Mineworkers and Construction Union (AMCU) encouraged the strike in response to disciplinary procedures against 40 employees following an illegal sit-in at Kusasalethu in January.

AMCU was not immediately available to comment.

Read also: Illegal Amcu strike hits Harmony shares

Harmony Gold, which produced just over 124 000 ounces of gold in the 2016 financial year at its Kusasalethu mine, said it had lost between 10 and 15 days of production but was unable to estimate the amount of ounces lost due to the strike.