Underground exploration has increased indicated resources at the Ilunga deposit by 409% to 205,000 oz, while the total overall rises 336% to 258,000 oz.
Grades of the indicated resource rose 17% to 4.71 g/t.
Shanta said it will prioritise work on Ilunga to define an underground reserve during the first quarter of 2017. This material was not included in its base case mine plan.
New Luika produced just under 81,900 ounces of gold in 2015 and should produce between 82-87,000 this year, but the focus has shifted underground to extend the mine’s life.
Shanta aims to have 70% of ore at New Luika mined below ground by next year.
Toby Bradbury, Shanta’s chief executive said he was delighted with the new resource at Ilunga.
“The deposit is a good grade, close to the plant and is likely to contribute to a meaningful increase in the mining reserve which in turn enhances shareholder value."
He added the majority of the Ilunga ounces will form part of a new high grade underground operation that would start as the Luika deposit is depleted in around 2020.
"The potential of this high grade extension creates the option to blend with, among others, the upgraded Elizabeth Hill Reserve declared earlier this year and thus extend the mine life by a number of years with a lot more prospective exploration still in play."
Shanta is also re-evaluating its licence at Singida, another Tanzanian prospect, and aims to boost the resource using the same drilling approach as Illunga.