The boost comes after consultancy Hellman & Schofield completed a new resource estimate for the Ekwai deposit and an updated estimate for the Koki deposit.
Both deposits were considered very similar to the project's key and nearby Horse-Ivaal-Trukai porphyry copper-gold system.
Based on a 0.2% copper cut-off grade, Ekwai was estimated to host an inferred resource of 173.55Mt at 0.38% copper and 0.23 grams per tonne gold for 664,686t of contained copper and 1.28Moz gold.
The Koki deposit was estimated to hold 451.97Mt of inferred resources at 0.37% copper and 0.25gpt gold for 1.66Mt of contained copper and 3.66Moz gold.
Joint venture partner Highlands Pacific commissioned this work and while these deposits are not part of the existing scope of the Frieda River feasibility study due in December, it suspects they will ultimately be part of the future mine.
"The Frieda River district contains one of the top undeveloped copper gold projects in the world and the fact that important additional resources like Ekwai and Koki exist so close to the HIT resource can only enhance the value and potential of the region," Highlands Pacific managing director John Gooding said.
The Frieda River prefeasibility study completed in 2010 estimated capital expenditure costs of $US5.3 billion for a 20-year mine life.
The open cut project is targeting 930,000t per annum of concentrate containing 246,000t copper and 379,000oz of gold in the first eight years of its life at C1 cash operating costs of 43c per pound or $1.12/lb without gold credits.
Xstrata assumed control of the project in January 2007 and must complete the feasibility study, due on December 21, to maintain its 81.82% interest.
Highlands Pacific owns 18.18% of the project and its shares were up 1c, or 6.7%, by midday (AEDT).