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OMI.V ·

London, August 26 th, 2025 . Orosur Mining Inc. ("Orosur" or the "Company") (TSXV/AIM:OMI), is pleased to announce an update on the progress of exploration activities at the Company's flagship, 100% owned, Anzá Gold Project ("Project") in Colombia, and its El Pantano Gold/Silver

Exploration Programs

Orosur Mining Inc - infill drilling continues to deliver, 71.85m @

6.13g/t Au.

• Assays from four more holes from the Pepas MRE infill program

include:

o PEP050 - 34m @ 2.33g/t Au from surface

o PEP051 - 61.3m @ 3.36g/t Au

o PEP052 - 71.85m @ 6.13g/t Au

• El Cedro soil sampling 45% complete - first samples submitted

for assay.

• Contracts being finalised for El Pantano (Argentina) drilling -

planned to commence mid-October.

London, August 26 th, 2025 . Orosur Mining Inc. ("Orosur" or the

"Company") (TSXV/AIM:OMI), is pleased to announce an update on the

progress of exploration activities at the Company's flagship, 100% owned,

Anzá Gold Project ("Project") in Colombia, and its El Pantano Gold/Silver

Project ("El Pantano") in Argentina.

Anzá - Colombia

As announced on 14 th July 2025, the Company took the formal decision to

commence infill drilling at its Pepas gold prospect at Anzá with the objective

of moving Pepas to a NI43 -101 compliant Mineral Resource Estimate

("MRE") by the end of the year.

The first several holes of this program (announced 17th July 2025), vindicated

this decision by returning exceptional widths and grades, especially hole

PEP045 which returned 62.3m @ 12.76g/t Au.

The drill program has been designed in conjunction with external consultants

to facilitate a MRE being calculated, with the multiple objectives of infilling

previous drilling, expanding beyond current drilling to define the boundaries,

and understanding th e geological controls upon mineralisation and the

variations in geology and grade across the deposit.

Holes will be drilled in an order that attempts to address these issues

concurrently.

These four holes announced today are a continuation of this program and

designed largely to infill to the required spacing to allow a MRE to be

calculated to a high level of confidence. Drilling continues to return thick

sequences of high-grade gold mineralisation, starting from surface or near

surface.

Importantly, drilling is also providing guidance as to grade and mineralogical

variation across the ore body that will allow our teams to define various

metallurgical domains that will in turn form the basis of more advanced

metallurgical studies that are planned to commence soon.

Hole Number From (m) To (m) Interval

(m) Au (g/t)

PEP050 0 34 34 2.33

including 9.65 12.65 3 3.71

including 23.3 25.4 2.1 9.4

PEP051 0 7.4 7.4 0.43

11.2 72.5 61.3 3.36

including 27.4 36.5 9.1 5.93

including 39.3 48.9 9.6 5.31

PEP052 0 4.4 4.4 2.24

9.4 81.25 71.85 6.13

including 29.95 48.4 18.45 13.51

65.2 71.2 6 9.11

PEP053 17 27.1 10.1 0.9

Table 1. Latest drill Intercepts, Pepas Prospect

Figure 2. Plan of holes

Figure 3. Section, PEP050

Figure 4. Section PEP051, PEP051 and PEP053

El Cedro - Anzá, Colombia

The El Cedro prospect is a large gold porphyry system, located toward

the south of the Anzá project, on the same granted exploration licence

as the Pepas and APTA deposits.

The Company has recommenced a large ridge and spur soil sampling

program that had been previously suspended due to seasonal rain and

access issues. This program is now roughly 45% complete, and it is

expected that the remainder of the program should be co mpleted by

mid-October 2025.

The first batch of 40 samples from the restarted program have been

submitted for assay this week, with results expected soon.

El Pantano - Argentina

The El Pantano Project is an early -stage gold/silver exploration project in

Santa Cruz province, southern Argentina.

The Project comprises approximately 550km2 of contiguous licences in the

prolific Deseado Massif region, roughly 45km from Anglo Gold's Cerro

Vanguardia mining camp.

The El Pantano Project is subject to an Exploration & Joint Venture ("JV")

agreement ("Agreement") with private Argentinean company DESEADO

DORADO S.A.S and its shareholders ("Deseado"), the details of which were

announced on February 15th 2022. The Company has earned a 51% interest

in the El Pantano Project and must spend an additional US$2m in the two

years from Feb 14th, 2025, in order to earn 100% ownership.

The Company has been carrying out regional exploration at El Pantano for

several years, including geological mapping, geochemical sampling, ground

magnetics and induced polarisation geophysical surveys. These work

programs have provided evidence suggestive of major rift -related low

sulphidation epithermal system, of the type that has led to the development

of major gold and silver deposits in the region.

Drill permits for El Pantano were obtained late in 2024, and the Company is

now finalising drill contracts with a view to commencing drilling in mid -

October 2025, the first drill program that has ever been undertaken anywhere

on the property.

Between 10 and 14 diamond holes are planned for a total of approximately

3000m, targeting geological structures and geochemical/geophysical

anomalies identified from previous work. Additional details will be provided

once more precise timing is finalised.

The area is very remote and largely unpopulated and thus substantial effort

has been required to plan and develop the necessary camp and access

infrastructure for a drilling program of this size.

The Deseado Massif is a major gold producing area in Argentina and thus

some necessary downstream infrastructure exists in the region. In particular,

an international laboratory company has a fire assay facility in the regional

town of Perito Moreno and thus a short assay turnaround time (for gold and

silver) is anticipated.

Orosur CEO Brad George commented:

"Pepas remains on track and the high bar set by the early holes continues to

be cleared on a regular basis. In the meantime, we are excited to be getting

close to opening a second drilling front on our El Pantano project in

Argentina. Early stage, but this is elephant country, and we like what we have

seen thus far".

Colombia - ANZÁ Project ("Project")

The Anzá Project is now 100% owned by the Company following completion

of a Share Purchase Agreement ("SPA"), announced 28 th November 2024,

whereby the Company purchased all of the shares of its previous JV partner;

Minera Monte Aguila ("MMA").

The Project, which is located 50km west of Medellin, is easily accessible and

boasts excellent infrastructure including water, power and communications

as well as a large exploration camp.

From September 2018 to November 2024, the Anzá Project was under the

control of its previous JV partner MMA, itself a 50/50 venture between the

world's two largest gold miners, Agnico Eagle Mines and Newmont Mining.

Prospects

The Company is currently focussed on three prospects within the Anzá

Project - Pepas, APTA and El Cedro. All three prospects are within the same

granted exploration title that is broken into two, non -contiguous pieces

(Figure 2).

Drilling is currently being undertaken at the Pepas prospect in the northern

extent of the Anzá Project (pre -acquisition) over 10km north of the central

base camp at APTA. In parallel, mapping and sampling is being undertaken

over the El Cedro porphyry system in the south of the project area.

Figure 5. Main prospects, licences pre-MMA acquisition

Holes Drilled post MMA Transaction

38 holes have been drilled at Pepas since the MMA Transaction in November

2024.

Assay results are tabulated below.

Hole Number From (m) To (m) Interval

(m) Au (g/t)

PEP012 0 66.75 66.75 5.64

PEP013 0 77.30 77.30 7.68

PEP014 0 75.1 75.1 5.58

PEP015 23.5 63.7 40.2 3.75

PEP016 61.6 105.3 43.7 3.13

PEP017 56.1 96.3 40.2 2.06

PEP018 0 54.1 54.1 6.01

PEP019 0 44.3 44.3 1.63

PEP020 0 54.65 54.65 1.94

PEP021 0 107.05 107.05 6.22

PEP022 0 76.3 76.3 7.24

PEP023 0 15 15 1.7

PEP024 9.24 15.6 6.35 1.99

PEP025 0 10.1 10.1 1.45

16.5 79 62.5 5.4

PEP026 0 14.8 14.8 0.57

43.6 72 28.4 2.52

PEP027 1 80.15 79.15 2.0

PEP028 29.5 60.85 31.35 1.61

PEP029 0 30.7 30.7 0.31

PEP030 0 77.9 77.9 0.32

115.6 122.6 7 0.31

PEP031B 28.15 41.1 12.95 0.73

74.1 95.9 20.8 0.3

PEP032 0 92 92 1.68

PEP033 0 21.3 21.3 5.88

PEP034 36 95 59 10.15

PEP035 0 11.4 11.4 2.71

PEP036B 0 40.45 40.45 0.62

PEP037 0 3 3 0.65

PEP038 0 16.8 16.8 0.68

PEP039 No significant intersections

PEP040 0 10.25 10.25 1.35

PEP041 34.35 66.1 31.75 2.01

PEP042 104.8 107.55 2.75 1.41

116.45 119.7 3.25 4.89

PEP043 No significant intersections