3 September 2026

Sunda Energy Plc

("Sunda" or "Sunda Energy" or the "Company")

Update regarding Prospective Resources for Philippines exploration prospect

Sunda Energy Plc (AIM: SNDA), the AIM-quoted exploration and appraisal company focused on hydrocarbon assets in the Asia-Pacific region, notes the announcement released today by Tetragon Energy Ltd (ASX: TET) ("Tetragon") of a material increase in Prospective Resources for the Halcon exploration prospect ("Halcon"), in Philippines Service Contract 80 ("SC 80"). Mid Case (2U) Prospective Resources for Halcon are now reported by Tetragon as 8.0 Tcf gross (3.0 Tcf net to Sunda's working interest). Tetragon also report a geological chance of success of 24%.

Full details can be found at the announcement released by Tetragon today (LINK).

SC 80, and adjacent Service Contract 81, lie in the offshore area of the Bangsamoro Autonomous Region of Muslim Mindanao in the Philippines.

Both Service Contracts are operated by Tetragon with a 37.5% working interest, with partners Sunda (37.5%), PXP Energy Corporation (PSE:PXP, 12.5%) and The Philodrill Corporation (PSE.OV, 12.5%).

Table 1: Halcon Prospective Resources recoverable gas gross and net as stated in Tetragon's announcement released today

The estimated Prospective Resources for the five key prospects at SC 80, including Halcon, were previously announced by Sunda on 8 October 2025 and based on a competent person report produced by Mitra Energy Inc. in 2015.

ENDS

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Qualified Person's Statement

Pursuant to the requirements of the AIM Rules - Note for Mining and Oil and Gas Companies, the technical information and resource reporting contained in this announcement has been reviewed by Dr Andrew Butler, Fellow of the Geological Society of London and member of the Society of Petroleum Engineers.  Dr Butler has more than 30 years' experience as a petroleum geologist. He has compiled, read and approved the technical disclosure in this regulatory announcement and indicated where it does not comply with the Society of Petroleum Engineers' standard.

Glossary:

1U                                    Denotes the low estimate qualifying as Prospective Resources. Reflects a volume estimate that there is a 90% probability that the quantities actually recovered will equal or exceed the estimate

2U                                    Denotes the mid estimate qualifying as Prospective Resources. Reflects a volume estimate that there is a 50% probability that the quantities actually recovered will equal or exceed the estimate

3U                                    Denotes the high estimate qualifying as Prospective Resources. Reflects a volume estimate that there is a 10% probability that the quantities actually recovered will equal or exceed the estimate

Bcf                                    Billion cubic feet of gas

Tcf                                    Trillion cubic feet of gas

Prospective Resources Quantities of petroleum that are estimated to exist originally in naturally occurring reservoirs, as of a given date. Crude oil in-place, natural gas in-place, and natural bitumen in-place are defined in the same manner

Notes Regarding Contingent and Prospective Resources

1.    Tetragon has prepared its Contingent Resources and Prospective Resources in accordance with the definitions and guidelines in the Society of Petroleum Engineers (SPE) 2018 Petroleum Resources Management System (PRMS). The PRMS defines prospective resources as those quantities of petroleum which are estimated, as of a given date, to be potentially recoverable from undiscovered accumulations.