Regis Resources (ASX:RRL) said the ore reserve at its McPhillamys Gold Project has been reinstated at 56 million tonnes at 1.1 grams per tonne gold for 1.89 million ounces in the probable category, according to a Friday Australian bourse filing.

The company said a new pre-feasibility study (PFS) demonstrates that at a AU$4,000 per ounce gold price, the project delivers average annual gold production of 190,000 ounces and an all-in sustaining cost (AISC) of AU$1,718 per ounce, with gross revenue of AU$7.1 billion.

The PFS shows a post-tax net present value of AU$1.13 billion at a 5.5% discount rate and an internal rate of return of 21.8%, with total pre-production capital of AU$1.08 billion, including AU$78 million of contingency and AU$77 million of capitalized pre-production operating costs, the filing added.

Regis is targeting a final investment decision (FID) in the first half of 2028, subject to permitting, including the Integrated Waste Landform, with the PFS not including consideration of prospects outside the McPhillamys deposit, such as Discovery Ridge and Kings Plains, which represent upside potential, it added.

The company's shares fell 3% in recent Friday trade.