The measured and indicated resources estimate, 120% higher than the last findings in 2011, was of 28.4 million tonnes at grades of 1.68 grams per tonne gold and 17.2gpt silver, which also amounts to a figure of 1.82Moz gold equivalent.
The upgraded total resource was 42.5Mt at 1.54gpt gold and 13.5gpt silver for 2.11Moz gold or 2.45Moz gold equivalent - a 20% increase from 2011.
Indochine chief executive officer Stephen Promnitz said the resource estimate importantly included about 400,000oz of contained gold from two recently drilled high-grade zones that averaged 5.4gpt gold.
Alternative modelling of the two high-grade zones also created the opportunity to target grades of nearly 20gpt gold.
"This could allow for the rapid development of an exploration adit to further drill high grade zones and potentially fast-track development at lower capital costs, with an improved return on investment in comparison with last year's prefeasibility study," Promnitz said.
"This is how the adjoining Porgera gold mine started."
A larger amount of near-surface oxide material was also found, which provided more opportunities for staged mine development.
"Fourteen other anomalies have been identified, but not drilled yet, within the Mt Kare licence, with two targets showing gold in stream samples," Promnitz said.
"Given the similarities to Porgera, a much larger mineralised system is indicated to exist at Mt Kare. Our priority is to consider multiple options for accelerated, lower cost development, factoring in a gold price more aligned to current levels, while exploring the high grade zones."
Last year, Indochine was aiming to lodge a mining licence application with the PNG government by late 2013.
The project is 15km southwest of Barrick Gold's Porgera mine in Enga province.