Montreal, Quebec--(Newsfile Corp. - August 20, 2026) - Sirios Resources Inc. (TSXV: SOI) (OTCQB: SIREF) (FSE: 377A) ("Sirios" or "the Company") announces the assay results of the first 5 holes totaling 1,753 m of Phase 1 drilling at its Cheechoo gold project, located in the Eeyou Istchee Baie-James region of Quebec, Canada.

Highlights from these first results include:

• 2.40 g/t Au over 48.5 m, including 77.65 g/t Au over 1.1 m (CH26-326)
• 1.49 g/t Au over 37.6 m (CH26-326)
• 1.16 g/t Au over 32.2 m, including 12.88 g/t Au over 1.5 m (CH26-327)
• 2.28 g/t Au over 10.3 m, including 10.39 g/t Au over 1.5 m (CH26-327)
• 0.77 g/t Au over 10.3 m (CH26-300E)

Visible Gold in 8 Drill Holes
Visible gold has been observed in several locations in 8 drill holes, including drill hole CH26-326, and 7 others for which assay results are pending. To date, 33 holes have been completed and four more are in progress for a total drilled length of 13,555 meters, including the extension of hole #300 (CH26-300E). Four drill rigs remain in operation at Cheechoo.

"We are pleased with the initial results of our 2026 summer drilling program," said Dominique Doucet, Head of Exploration for Sirios. "From the very first holes, good results were obtained both outside and within the conceptual pit of our resources, confirming the potential for expansion of the deposit in the tonalite as well as the depth extension of the metasedimentary zone to the east."

"These preliminary results, which represent less than 10% of the planned drill holes, support our thesis that the resource at Cheechoo has the potential to become more significant than indicated in the 2025 resource estimate," said Jean-Félix Lepage, CEO of Sirios. "With four active drill rigs, we anticipate completing Phase 1 in September and launching the updated resource estimate thereafter."

Figure 1: Locations of observed visible gold

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2026 DRILL PROGRAM: ASSAY RESULTS FROM FIRST DRILL HOLE

Figure 2: Location of drill holes CH26-326 to CH26-329, and extension of CH26-300E

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Furthermore, the onsite analysis campaign involved scanning 24,299 m of core, including drill holes from the current campaign, using Élémission's ECORE Laser-Induced Breakdown Spectroscopy (LIBS) instrument. The analysis campaign will continue until mid-September.

Quality Assurance and Quality Control
The drill cores were described and sampled by Sirios personnel at the Cheechoo Exploration Camp. The cores were split into two halves, one of which was sent to a certified commercial laboratory for analysis, and the other was retained for future reference. Following a strict analytical quality assurance and quality control program, blanks and certified reference materials were incorporated into the sampling sequence. Samples were analyzed for gold, on approximately 500 g of crushed material, using the Photon Assay™ method by the MSALABS laboratory located in Val-d'Or. Samples containing visible gold were analyzed using the entire crushed sample with the Photon Assay™ method.

Qualified Person
The scientific and technical content of this press release has been reviewed and approved by Dominique Doucet, P.Eng., Head of Exploration at Sirios, a Qualified Person as defined by Canadian National Instrument 43-101.

Additional information on previously announced marketing agreement
On April 1st, 2026, the Company announced that it has entered into a marketing services agreement with Resources Stock Digest ("RSD"). RSD did not receive common shares or options as remuneration, but the owners of RSD are shareholders of the Company.

About the Cheechoo Project
Cheechoo is located approximately 15 km from the Éléonore mine and near infrastructure, including roads and hydroelectric facilities, in the Eeyou Istchee Baie-James region of Canada. Cheechoo is in the resource development stage, with 35 Mt of indicated resources at 1.12 g/t (1,262 koz) and 42.7 Mt of inferred resources at 1.23 g/t (1,688 koz) (see NI 43-101 Technical Report on the Cheechoo Project with an Updated Mineral Resource Estimate for the Cheechoo Gold Deposit, Eeyou Istchee James Bay, Québec, dated August 22, 2025 and deposited on the Company's website and on SEDAR+). In addition, a conceptual exploration target of 31 to 40 million tonnes of mineralization grading between 1.27 and 1.45 g/t Au has been estimated.

About Sirios
Sirios Resources is a Quebec-based mineral exploration company focused on developing its Cheechoo gold deposit, as well as exploring and advancing its other high-potential gold projects in the Eeyou Istchee James Bay region of Canada. On December 11, 2025, Sirios announced the details of the acquisition of OVI Mining, a milestone in the company's history.

Cautionary Note Regarding Forward-Looking Statements
This press release contains "forward-looking statements" within the meaning of applicable Canadian securities laws, based on expectations, estimates, and projections as of the date of this press release. Forward-looking statements involve risks, uncertainties, and other factors that could cause actual events, results, performance, expectations, and opportunities to differ materially from those expressed or implied in such forward-looking statements. Factors that could cause actual results to differ materially from those indicated in these forward-looking statements include, but are not limited to: capital and operating costs that differ materially from estimates; the preliminary nature of metallurgical test results; delays or failures in obtaining required governmental, environmental, or other approvals; uncertainties regarding the availability and cost of necessary future financing; changes in financial markets; inflation; fluctuations in metal prices; delays in project development; other risks associated with the mineral exploration and development industry; and the risks disclosed in the Company's public filings on SEDAR+ at www.sedarplus.ca. Although the Company believes that the assumptions and factors used to prepare the forward-looking statements contained in this press release are reasonable, readers should not place undue reliance on this information, which is valid only as of the date of this press release, and there is no guarantee that these events will occur or occur within the timeframes indicated. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by applicable law.

Neither the TSX Venture Exchange nor its regulatory services provider (as defined in the policies of the TSX Venture Exchange) accepts any responsibility for the adequacy or accuracy of this press release.

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