The company said early in April state rules to prevent transmission of the virus had made business impractical, paralysing the company's supply chain and the free movement of staff, and causing "significant operational delays and work constraints".

However, it has managed to extend Pumpkin Hollow's main shaft to its final depth of 650m while the rest of the site has been on care and maintenance.

Nevada Copper CEO Evan Spencer said completion of the final furnishing phase of shaft construction would boost the reliability of the mine when copper concentrate production was restarted.

Shaft ramp work, excavation of a loading pocket, and construction of a 25-person underground safety refuge chamber and underground fuel delivery station, had also been completed.

Meanwhile, Redpath USA is continuing lateral underground development underground and resource definition drilling to support mine planning.

The surface ore stockpile now had more than 95,000 tons of material on it, Nevada Copper said.

It said planning was "well advanced" for a likely September quarter restart.