Ms. Elaine Ellingham reports

OMAI GOLD FILES NI 43-101 TECHNICAL REPORT SUPPORTING A PRELIMINARY ECONOMIC ASSESSMENT INDICATING AFTER-TAX NPV5% OF $4.0 BILLION AT A $3,600/OZ GOLD PRICE FOR ITS OMAI GOLD PROJECT

Omai Gold Mines Corp. has filed a National Instrument 43-101 technical report dated Oct. 2, 2026, on SEDAR+ in support of the preliminary economic assessment (PEA) announced on Aug. 19, 2026, for the Wenot open-pit and Gilt underground deposits on its wholly owned Omai gold project in Guyana. The report was prepared under the supervision of David Robson, PEng, of SLR Consulting (Canada) Ltd., who is independent of the company and a qualified person in accordance with National Instrument 43-101. (All dollar amounts are in U.S. dollars, unless otherwise stated.)

Elaine Ellingham, president and chief executive officer, commented: "Delivering this technical report is a major milestone for the company, which outlines average annual production of approximately 351,000 ounces of gold over an 18-year mine life with peak production of 436,000 ounces. This would be a significant contributor to Guyana's future economy, and we look forward to continuing to expand and optimize this project while we advance towards a feasibility study."

On Aug. 19, 2026, the company issued a news release announcing the preliminary economic assessment with the following highlights:

• 351,488 ounces (oz) of gold (Au) per year projected average production over the LOM (life of mine), with peak year gold production reaching 435,667 ounces;
• 6,327,000 ounces of gold projected LOM payable production over 18 years;
• $4.0-billion after-tax net present value at a discount rate of 5 per cent at base case $3,600 per oz gold, increasing to $5.5-billion at $4,200 per oz gold;
• 24-per-cent after-tax internal rate of return at $3,600 per oz gold, increasing to 30 per cent at $4,200 per oz gold;
• $1.427-billion initial capital and sustaining and growth capital of $928-million over LOM;
• 4.1-year payback at $3,600 per oz gold, decreasing to 3.4 years at $4,200 per oz Au;
• $1,501 per oz gold average cash operating costs and all-in sustaining costs (AISC) (3) of $1,608 per oz;
• $8.093-billion cumulative after-tax cash flows (4) over 18 years;
• 1.35 grams per tonne (g/t) Au average head grade and process recovery of 93 per cent;
• 5.9:1 average strip ratio for the open-pit LOM.

Full details are presented in the report filed on SEDAR+ and the company's website.

About Omai Gold Mines Corp.

Omai Gold Mines is a Canadian gold exploration and development company focused on rapidly expanding the two orogenic gold deposits at its 100-per-cent-owned Omai gold project in mining-friendly Guyana, South America. The company has established the Omai gold project as one of the fastest-growing and well-endowed gold camps in the prolific Guiana Shield.

On Aug. 19, 2026, Omai announced a preliminary economic assessment (PEA) (1)that includes the large Wenot open-pit deposit and the adjacent Gilt underground deposit. The PEA supports a mine plan to produce 6.3 million ounces of gold over an 18-year mine life. Average gold production is projected at 351,000 ounces per year. At the $3,600-per-oz base case, this supports a $4.0-billion net asset value discounted at 5 per cent. This PEA is based on a mineral resource estimate (2) of 2.5 million ounces indicated averaging 2.04 g/t Au in 38.1 million tonnes and 5.5 million ounces inferred averaging 1.59 g/t Au in 106.6 million tonnes. Drilling on the 50,000-metre drill program is continuing with five rigs.

As a past-producer, Omai significantly benefits from both the historical record of economic gold extraction and the existing infrastructure, including a cleared site, an on-site airstrip, a tailings facility, known metallurgy, and road connections to the two largest cities in Guyana, Georgetown and Linden.

Qualified persons

The preliminary economic assessment was prepared by SLR Consulting (Canada) Ltd. The technical content in this news release has been reviewed by the following qualified persons (QPs): David M. Robson, PEng, Goran Andric, PEng, Jeff Sepp, PEng, Linda Dufour, PEng, Stephan Theben, DiplIng, SME RM, and Alan J. San Martin, PEng.

Elaine Ellingham, PGeo, is a qualified person under National Instrument 43-101, Standards of Disclosure for Mineral Projects, and has reviewed and approved the technical information contained in this news release. Ms. Ellingham is a director and officer of the company, and is not considered to be independent for the purposes of National Instrument 43-101.

(1) The PEA was announced Aug. 19, 2026. A PEA is preliminary in nature and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves, and there is no certainty that the PEA will be realized. Mineral resources that are not mineral reserves do not have demonstrated economic viability.

(2) Omai Gold Mines news release, titled "Omai Gold Increases Indicated Mineral Resources to 2.5 Moz Au at 2.04 g/t Au (38.1 Mt) and Inferred to 5.5 Moz Au at 1.59 g/t Au (106.6 Mt) with Expansion of Wenot and Gilt Deposits," dated April 14, 2026. A technical report will be filed on SEDAR+ to include the PEA and the April mineral resource estimate within 45 days of Aug. 19, 2026.

(3) AISC is the sum of operating costs, off-site costs, royalty payments and sustaining capital costs, divided by payable gold ounces produced.

(4) Cumulative after-tax cash flows are defined as gross revenues less royalty payments, preproduction capital costs, operating costs, sustaining and growth capital costs, taxes, and reclamation and closure costs.

We seek Safe Harbor.