Cheechoo Gold Project: Mineral Resource Estimate Update Underway Based on New Model

Montreal, May 28, 2025 - Sirios Resources Inc. (TSXV: SOI) (OTCQB: SIREF) ("Sirios") is pleased to announce that an update of the Mineral Resource Estimate (MRE) for its flagship Cheechoo Gold Project in Eeyou Istchee James Bay, Québec, is well underway, with results anticipated as soon as this summer. This update is driven by the adoption of a new game-changing geological and structural model that significantly redefines the deposit's potential.

A Transformative Geological Model
Developed in collaboration with leading consultants in resource modeling and applied structural geology, the new model is grounded in a comprehensive analysis of drilling data and geological structures. This work has uncovered previously unrecognized structural controls on gold mineralization, resulting in a redefinition of key mineralized zones and corridors. An interactive 3D viewer of the new model will be made available on Sirios' website upon publication of the updated MRE.

Key Anticipated Impacts
For the first time, the forthcoming resource estimate is expected to include an underground component-representing a major advancement over the December 2022 estimate. This addition paves the way for expanded resource development through future drilling initiatives.

"Our team's dedication over the past year is coming to fruition as we integrate new insights and data into the upcoming Mineral Resource Estimate," stated Dominique Doucet, President and CEO of Sirios Resources. "We are confident that the new estimate will showcase Cheechoo's substantial resource development potential and reinforce its status as a premier gold project in Québec."

The MRE update is being conducted by PLR Resources Inc., a trusted geological consulting firm founded by Pierre Luc Richard, a recognized expert in mineral resource estimation who has authored and coordinated more than 100 technical reports under National Instrument 43-101.

Livestream Event: May 28
To provide further details on developments at the Cheechoo Gold Project and the ongoing resource estimate update, Sirios will host a livestream event later today.

Attendees will have the opportunity to ask questions following the presentation. The livestream will be held on Zoom, with sessions offered in both French and English:

Webinar in French: 1:00 p.m. (EDT)
https://us06web.zoom.us/j/83341809688?pwd=3d2f1f1WmzfDP7zF0FyeNpazoNXzra.1

Webinar in English: 2:00 p.m. (EDT)
https://us06web.zoom.us/j/88567968164?pwd=dwORJwp39XomdTZ25QMqycbm9baiWB.1

About the Cheechoo Project
Located less than 15 km from Dhilmar Ltd.'s Éléonore gold mine in Quebec's Eeyou Istchee James Bay territory, the Cheechoo Project-100% owned by Sirios-hosts an untapped gold deposit with outstanding potential for expansion and development.

The 2022 Mineral Resource Estimate (MRE) reported, for an open-pit model:

• Indicated resources: 1.4 million ounces at an average grade of 0.94 g/t Au;
• Inferred resources: 500,000 ounces at an average grade of 0.73 g/t Au.

Underground mining scenarios have not been evaluated in this MRE.
Source: BBA, Mineral Resource Estimate Update for the Cheechoo Project, 23/12/2022

Learn more about Cheechoo at sirios.com/en/cheechoo.

About Sirios
Sirios Resources Inc. (TSXV: SOI) (OTCQB: SIREF) is a Quebec-based mineral exploration company focused on developing its 100%-owned Cheechoo Gold Project, located in Eeyou Istchee James Bay, Canada.

About PLR Resources
PLR Resources specializes in mineral resource estimates and project evaluations and offers a wide variety of services, from grassroots exploration planning to feasibility studies and mining operation optimization, serving clients that include juniors, major operators as well as financial experts seeking reliable and realistic advice.

Cautionary note regarding forward-looking statements
This news release contains "forward-looking information" within the meaning of applicable Canadian securities legislation based on expectations. estimates and projections as at the date of this news release. Forward-looking information involves risks, uncertainties and other factors that could cause actual events, results. Performance, prospects and opportunities to differ materially from those expressed or implied by such forward-looking information. Factors that could cause actual results to differ materially from such forward-looking information include, but are not limited to, capital and operating costs varying significantly from estimates; the preliminary nature of metallurgical test results; delays in obtaining or failures to obtain required governmental, environmental or other project approvals; uncertainties relating to the availability and costs of financing needed in the future; changes in equity markets; inflation; fluctuations in commodity prices; delays in the development of projects; the other risks involved in the mineral exploration and development industry; and those risks set out in the Company's public documents filed on SEDAR at www.sedarplus.ca. Although the Company believes that the assumptions and factors used in preparing the forward-looking information in this news release are reasonable, undue reliance should not be placed on such information, which only applies as of the date of this news release, and no assurance can be given that such events will occur in the disclosed time frames or at all. The Company disclaims any intention or obligation to update or revise any forward-looking information, whether as a result of new information, future events or otherwise, other than as required by law.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
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