Brightstar Resources (ASX:BTR) began an underground drilling program at the Fish Mine within the Laverton gold project in Western Australia, according to a Thursday Australian bourse filing.

The program will be completed in two phases, and it includes a substantial drill-out of deeper mineralization, targeting the conversion of inferred mineral resources beneath the existing mine plan into higher levels of classification.

Ongoing mine development by Brightstar's owner-operator mining team at Fish is advancing ahead of schedule.

The firm's shares fell 2% in recent trading on Thursday.