A legal firm in the United States has filed a law suit against a leading South African gold mining company, Sibanye-Stillwater, on behalf of the company's shareholders.

Bernstein Liebhard LLP says it is trying to recover shareholders' losses after a series of deaths at the company's mines led to a drop in its share price.

There have been 22 deaths since the beginning of the year.

Sibanye-Stillwater - one of the 10 largest gold producers globally - said it would "vigorously defend" against any claims.

Earlier this week, the chairman of South Africa's parliamentary committee on mineral resources, Sahlulele Luzipo, said the situation should be viewed as a national crisis, and suggested the company might have its licence withdrawn over safety concerns.