Poland’s state-run mining company KGHM Polska Miedź (KGHM) is reportedly planning to divest its Robinson and Carlota copper mines in the US.

Two sources told Reuters that the proceeds from the sale of the two mines, which are valued at around $500m, will be used by the company to reinvest in its domestic operations.

Located in White Pine County, Nevada, the Robinson mine includes three large pits.

The Carlota copper mine, which is located in the Miami-Globe mining region of Arizona, commenced production in 2008.

The news agency reported one of the sources as saying that the two mines considered for sale by KGHM are expected to attract interest from smaller mining companies or private equity firms in North America.

KGHM was cited by Reuters as saying in an emailed statement: “Scenarios for individual assets are at various stages of advancement.”

The firm said it would continue to work on improving the key assets’ value.

Since the company’s expansion was probed in 2015 by the conservative Law and Justice (PiS) party, KGHM has been reviewing and considering the potential sale of some of its foreign assets.

The company is also considering investing in core and domestic assets, including copper and silver mines and copper smelters.

Moreover, investors are keen on the plans by KGHM over its Sierra Gorda open-pit copper and molybdenum mine in Chile.

KGHM has a 55% stake in the mine while other partners include Sumitomo Metal Mining (31.5%) and Sumitomo Corporation (13.5%).

The move comes as Sumitomo Metal Mining said it is reviewing options regarding the Sierra Gorda mine last year, including a potential sale.

However, KGHM CEO Marcin Chludzinski told Reuters last month that the company is considering its stake in the Sierra Gorda mine as ‘optimal’.