Newmont Corp. sent Barrick Mining Corp. a so-called notice of default after finding evidence of alleged mismanagement at a Nevada joint venture, escalating tensions between the partners in a key US mining region.

Newmont Corp. wants Barrick Mining Corp. to address what it says is underperformance at their joint venture mining operations in Nevada before its partner proceeds with an initial public offering of its North American assets.

A multi-billion-dollar gold project owned by the world’s biggest bullion producer has been invaded by illegal diggers in northern Peru, according to a top government official.