The company said the study of the joint venture project with MOD Resources Limited supports the start of a 30-hole resource drilling programme targeting high-grade veins with underground mining potential.
So far 45 drill holes at the T3 have returned significant vein hosted copper mineralisation intersections below, down-dip and along strike from the planned open pit.
"We are very encouraged by the initial findings of the T3 Underground Project investigations and the prospect that room-and-pillar underground mining of the high-grade copper/silver veins, developed simultaneously to the planned T3 Open-Pit mine could make a substantial contribution to the T3 profitability," said Metal Tiger chief executive Michael McNeilly.
"Sharing a planned central scalable processing plant at T3 between both the T3 surface and underground mining operations and possible neighbouring deposits is an attractive proposition in the precursory modelling."
The joint venture will work towards the release of a T3 scoping-study by mid-2018.
Thai report received for mine restart projects
In a separate statement, the company said it had received a final report from Groundwater Research Institute, at the Khon Kaen University in Thailand, in relation to the Song Toh and Boh Yai lead-zinc-silver projects.
It is part of a development plan designed to bring the two mines back online, following an IPO of the joint venture vehicle KEMCO Mining PLC.
The report - "Hydrogeology near the planned Underground Lead-Zinc Mining at Song Toh and Boh Yai areas in Kanchanburi Province" - is based on six months of field and lab work.