Assays from four daughter diamond drill holes targeting the underground orebody at depth included the highlight of 94m at 4.4g/t gold from 1,305.7m.
Assays from drilling at the B Shoot included 27.18 grading 8.7g/t, which the company said had potential to add stopes into the near-term mine plan, and intercepts from a new target in the 242 trend footwall included 6.8m at 8.2g/t, pointing to additional production potential.
"We believe that Wassa is significantly larger than the current mineral resource estimate suggests and during 2018 we will continue to test its extensions through further drilling," president and CEO Sam Coetzer said.
Wassa's current underground reserve stands at 5.8 million tonnes at 4.21g/t gold for 742,000 ounces.
The company is aiming to produce 230,000-255,000 ounces of gold this year at a cash operating cost of US$650-730/oz from its Wassa and Prestea mines in Ghana.
Shares in the company have traded between C75c-$1.33 over the past year and were up 3.85% to 94.5c yesterday.