Saguenay, Quebec - Newsfile Corp. - August 24, 2026 - First Phosphate Corp (NASDAQ: PHOS) (CSE: PHOS) (OTCQX: FRSPF) (FSE: KD0) ("First Phosphate" or the "Company") is pleased to announce that the Company has filed its updated Mineral Resource Estimate ("MRE") Technical Report for the Bégin-Lamarche project located 50 km northwest of the City of Saguenay, Quebec, Canada (the "Deposit"). The Technical Report titled "Technical Report and Updated Mineral Resource Estimate of The Bégin-Lamarche Phosphate Property, Saguenay - Lac Saint-Jean Region, Northern Quėbec" dated August 24, 2026, with an effective date of May 1, 2026, was prepared by P&E Mining Consultants Inc. in accordance with National Instrument 43-101 - Standards of Disclosure for Mineral Projects and supports the disclosures made by the Company in its news release dated May 26, 2026. A full copy of the Report is available on the First Phosphate website at https://firstphosphate.com/projects/begin-lamarche-3 and can be found at SEDAR+ (www.sedarplus.ca) under the Company's issuer profile. MRE Highlights include:

• The updated MRE includes a 378% increase in Indicated Mineral Resources over the Company's Initial MRE dated September 9, 2024.
• Measured pit-constrained Mineral Resource: 6.2 Mt @ 7.70% P₂O₅ (phosphate).
• Indicated pit-constrained Mineral Resource: 198.5 Mt @ 6.00% P₂O₅.
• Inferred pit-constrained Mineral Resource: 89.5 Mt @ 6.16% P₂O₅.
• The Deposit remains open at depth.
• Metallurgical test work indicates an anticipated apatite concentrate grade of 40.4% P₂O₅ at an 88% process recovery rate, with very low levels of potentially deleterious elements, and has been qualified for production of battery-grade phosphoric acid for lithium iron phosphate ("LFP") battery with a conversion ratio of 91.1%.
• The Deposit is located next to existing road and hydroelectric infrastructure and at only 70 km driving distance from the deep-sea Port of Saguenay.
• The Deposit benefits from definitive, long-term, partially prepaid offtake from an existing, creditworthy partner.
• Apatite (phosphorus, phosphate) is listed on the critical minerals lists of Québec, Canada, the United States and the European Union.

The Bégin-Lamarche Deposit Updated Optimized Pit Shell Video available at: https://www.youtube.com/watch?v=4TV4WoC_Jhc&feature=youtu.beQualified Person The Qualified Person, independent of the issuer, responsible for estimating the Mineral Resources of the Begin-Lamarche Property, within the meaning of NI 43-101, is Mr. Antoine Yassa, P.Geo., of the firm P&E Mining Consultants Inc. Mr. Yassa has read this press release and confirms that the scientific and technical information in this press release for accuracy and compliance with NI 43-101. The scientific and technical disclosure for First Phosphate included in this News Release have been reviewed and approved by Steeve Lavoie, P.Geo. Mr. Lavoie is Chief Geologist of the Company and a Qualified Person under National Instrument 43-101 Standards of Disclosure of Mineral Projects ("NI 43-101"). About First Phosphate Corp First Phosphate (NASDAQ: PHOS) (CSE: PHOS) (OTCQX: FRSPF) (FSE: KD0) is a mineral exploration and development and clean technology company dedicated to building and reshoring a vertically integrated mine-to-market supply chain for the production of LFP batteries in North America. Target markets include energy storage, data centers, robotics, mobility, and national security. First Phosphate's flagship Bégin-Lamarche property, located in Saguenay-Lac-Saint-Jean, Québec, Canada, represents a rare North American igneous phosphate resource producing high-purity phosphate characterized by very low levels of impurities. For additional information, please contact: Steeve Lavoie Chief Geologist Tel: +1 (418) 815-5416 Investor Relations: https://firstphosphate.com/investors General Inquiries: https://firstphosphate.com/contact Website: www.FirstPhosphate.comFollow First Phosphate: X: https://twitter.com/FirstPhosphate LinkedIn: https://www.linkedin.com/company/first-phosphate/Forward-Looking Information and Cautionary StatementsThis news release contains certain statements and information that may be considered "forward-looking statements" and "forward looking information" within the meaning of applicable securities laws. In some cases, but not necessarily in all cases, forward-looking statements and forward-looking information can be identified by the use of forward-looking terminology such as "plans", "targets", "expects" or "does not expect", "is expected", "an opportunity exists", "is positioned", "estimates", "intends", "assumes", "anticipates" or "does not anticipate" or "believes", or variations of such words and phrases or statements that certain actions, events or results "may", "could", "would", "might", "will" or "will be taken", "occur" or "be achieved"...