Toronto, Ontario--(Newsfile Corp. - May 28, 2026) - Montero Mining and Exploration Ltd. (TSXV: MON) (OTC Pink: MXTRF) (FSE: ES0) ("Montero" or the "Company") is pleased to announce that drilling has commenced at the Elvira Gold Project in Chile. The simplified geology and concession area are shown in Figure 1.

Figure 1: Elvira Project concession boundary and simplified geology displayed on a topographic base image, illustrating the broader structural and lithological framework.

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The current first-pass drill program is designed to test the highest-priority integrated drill targets defined by Montero from its geological, geochemical, and geophysical review of the Elvira system.

The initial phase of drilling is designed to test the strongest converging vectors from the upper gold-bearing epithermal system into the deeper porphyry Cu-Au domain. These vectors include surface geochemistry, deep chargeability, resistivity, structural interpretation, historical drilling, and project-scale alteration mapping derived from ASTER and Sentinel-2 imagery.

Initial drilling has commenced with MON-ELV-01, a priority hole designed to test the central part of the >22.5 mV/V chargeability anomaly at depth beneath the historical drillhole EL-12 area (Figures 2 to 5). This target was prioritised because it integrates several of the strongest vectors identified by Montero on the project; including proximity to surface gold anomalism, a strong chargeability anomaly at depth, coincident resistivity features, favourable deep structural setting, the historical gold intersection in EL-12 (Buena Vista Gold reported drillhole EL-12 intersected 4 m @ 4.9 g/t Au from 264-268 m, including 17.85 g/t Au, this is interpreted by Montero as a high-grade feeder/upflow position), and a broader alteration footprint interpreted from ASTER and Sentinel-2 imagery. Montero also considers the target to be supported by Fathom's modelling work, which indicates potential for a deeper porphyry system beneath Elvira. The hole is intended to test the interpreted link between the shallow epithermal gold system, a possible feeder setting in the EL-12 area, and a deeper porphyry Cu-Au target.

Dr. Tony Harwood, President and Chief Executive Officer of Montero, commented: "Montero's work at Elvira has materially improved our understanding and highlighted the scale of the mineral system. Drillhole MON-ELV-01 is designed to test a strong chargeability anomaly at depth beneath historical drill intercept, where Montero interprets a compelling epithermal feeder to porphyry Cu-Au target."

The current first-pass drilling program is expected to comprise four initial holes for approximately 2,025 metres, subject to drilling conditions and operational progress. Follow-up holes may be adjusted based on results from the initial phase.

Following MON-ELV-01, the initial sequence is expected to test:

• The EL-09/ELRC-16/ELRC-22 area, where historical drilling supports a copper vector toward a deeper chargeability target.
• The epithermal cap-to-porphyry link target.
• The principal resistive high-sulphidation feeder target.

The Company has completed site preparation, logistics planning and field mobilization, together with its contractors, to support the initial drill campaign.

Historical drillhole and assay information referenced in this release are derived from public-domain disclosure by Buena Vista Gold Corp. Montero has used this information as part of its current geological interpretation and drill targeting; however, readers are cautioned that historical results may not be directly comparable to current reporting standards.

Figure 2: Geological map on a satellite image showing the planned location of drillhole MON-ELV-01 relative to anomalous surface gold, silver and copper values.

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Figure 3: West-east section through MON-ELV-01 showing the interpreted IP resistivity and high chargeability anomaly and the conceptual deeper target zone, together with the surface gold anomaly and historic drillhole EL-12 which intersected gold at depth.

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Figure 4: Subsurface geophysical map showing drillhole MON-ELV-01 relative to IP resistivity anomaly and deep chargeability anomaly, together with the surface gold anomaly and historical drillhole EL-12 which intersected value at depth.

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Figure 5: Drill rig on site for collar preparation with ancillary equipment and supplies.

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Qualified Person

The scientific and technical information contained in this press release has been reviewed and approved by Mr. Marcial Vergara, B.Sc., and Mr. Mike Evans, M.Sc. Pr.Sci.Nat., each a Qualified Person as defined by National Instrument 43-101 - Standards of Disclosure for Mineral Projects, and independent consulting geologists to the Company.

About Montero

Montero Mining and Exploration Ltd. is a Canadian exploration company focused on gold and copper exploration in Chile. Montero holds a 100% interest in the Avispa copper-molybdenum project in the Palaeocene Porphyry Cu-Mo Belt of northern Chile and has an option to acquire the Elvira and Potrero gold projects in the Maricunga Gold Belt. These projects are being advanced through ongoing exploration activities.

Montero is listed on the TSX Venture Exchange under the symbol MON and has 8,453,833 Common Shares and 735,383 stock options outstanding.

Neither 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.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING INFORMATION: This news release includes certain "forward-looking information" within the meaning of applicable Canadian securities laws. Forward-looking information in this press release includes, but is not limited to, statements regarding: the integration and interpretation of geological, geochemical and geophysical data; the application of artificial intelligence and machine learning tools; the identification, evaluation or prioritization of areas for further exploration; the potential for mineralization; and the timing or scope of future exploration activities, including any potential drilling. Generally, forward-looking information can be identified by the use of forward-looking terminology such as "plans", "expects", "does not expect", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", "does not anticipate", or "believes", or variations of such words and phrases, or statements that certain actions, events or results "may", "could", "would", "might" or "will" occur or be achieved. Such information is based on information currently available to Montero and on assumptions management believes are reasonable as of the date of this news release. Forward-looking information is subject to known and unknown risks, uncertainties and other factors that may cause actual results, level of activity, performance, or achievements of the Company to be materially different from those expressed or implied by such forward-looking information. These risks and uncertainties include, but are not limited to: risks related to mineral exploration and development activities; uncertainties inherent in the interpretation of geological and geophysical data; the speculative nature of mineral exploration; commodity price fluctuations; changes in general market conditions; regulatory approvals and permitting risks; availability of financing; operational and technical risks; and other risk factors described in the Company's public disclosure documents filed on SEDAR+. There can be no assurance that such forward-looking information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Readers are cautioned not to place undue reliance on forward-looking information. Montero does not undertake to update any forward-looking information, except in accordance with applicable securities laws.

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