(Bloomberg) -- Polyus PJSC, Russia’s largest gold producer, said its untapped Sukhoi Log deposit in Siberia holds the world’s biggest reserves.

An audit showed Sukhoi Log has 40 million ounces of proven reserves as measured by international JORC standards, with an average gold content of 2.3 grams per ton, according to Chief Executive Officer Pavel Grachev. That means the field -- accounting for more than a quarter of Russian gold reserves -- is bigger than Seabridge Gold Inc.’s KSM Project in Canada and Donlin Gold in Alaska.

“The estimate of the reserves is an important milestone in development of the field,” Grachev said in interview in Moscow.

Polyus said earlier this year that it would focus on smaller projects and reducing its debt ratio in the coming years before developing the giant field. The company plans to announce details on expected production and investment at Sukhoi Log once a pre-feasibility study is ready by year-end. It previously said that costs could reach $2.5 billion, with annual output totaling about 1.6 million ounces.

More on Sukhoi Log:

  • The audit shows that as well as economically mineable reserves, the deposit has 67 million ounces of total resources, up from 63 million ounces previously estimated.
  • That figure may rise after more drilling and studies.
  • Main investment is due to start in 2023. Polyus has already started spending on infrastructure for the project, including co-investing with the government on the reconstruction of a local airport.

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