RNS Number : 5523T Great Southern Copper PLC 07 September 2026 THIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION AS STIPULATED UNDER THE UK VERSION OF THE MARKET ABUSE REGULATION NO 596/2014 WHICH IS PART OF ENGLISH LAW BY VIRTUE OF THE EUROPEAN (WITHDRAWAL) ACT 2018, AS AMENDED. ON PUBLICATION OF THIS ANNOUNCEMENT VIA A REGULATORY INFORMATION SERVICE, THIS INFORMATION IS CONSIDERED TO BE IN THE PUBLIC DOMAIN. 07 September 2026 Great Southern Copper plc ("GSC" or the "Company") Notice of Annual General Meeting Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold-silver exploration in Chile, announces that its 2026 Annual General Meeting ("AGM") is to be held at Gowlings LLP, 4 More London Riverside, London, SE1 2AU on Wednesday 30 September at 10:00am. The Notice of AGM and form of proxy will be posted to shareholders in due course. The documents will also be uploaded to the Company's website at www.gscplc.com in due course. In accordance with UKLR 6.4.1, copies of the Notice of AGM and Form of Proxy have been submitted to the National Storage Mechanism ("NSM") and will shortly be available for inspection at: https://data.fca.org.uk/#/nsm/nationalstoragemechanism The Company notes that the digitally structured electronic format of the Annual Financial Report (comprising xHTML with ESEF/UKSEF tagging) will be submitted to the NSM in due course. Contact Details: Great Southern Copper plc https://gscplc.com/link/egL9vr Sam Garrett, Chief Executive Officer +44 (0) 20 4582 3500 SI Capital Limited Nick Emerson +44 (0) 1483 413500 BlytheRay Megan Ray / James Mulligan +44 (0) 20 7138 3204 gsc@blytheray.com Subscribe to our news alert service: https://gscplc.com/auth/signup Notes for Editors: About Great Southern Copper Great Southern Copper PLC is a UK-listed mineral exploration company focused on the discovery of copper-gold-silver deposits in Chile. The Company has the option to acquire mining rights to 100% of Especularita project in the under-explored coastal belt of Chile that is prospective for large scale copper-gold-silver deposits. Chile is a globally significant mining jurisdiction being the world's largest producer and exporter of copper. The Especularita Project is located in the coastal metallogenic belt of Chile which hosts significant copper mines and deposits, including Teck's Carmen de Andacollo copper mine, and boasts excellent access to infrastructure such as roads, power and ports. Significant historical small-scale and artisanal workings for both copper and gold are readily evident in the exploration project area. The coastal belt offers deposit type optionality for copper including porphyry and IOCG style deposits as well as newly recognised intrusive-related copper and gold deposits. Great Southern Copper is strategically positioned to support the global market for copper - a critical battery metal in the clean energy transition around the world. The Company is actively engaged in exploration and evaluation work programmes targeting both large tonnage, low to medium grade Cu-Au as well as high-grade Cu-Ag-Au deposits. Further information on the Company is available on the Company's website: https://gscplc.com This information is provided by RNS, the news service of the London Stock Exchange. RNS is approved by the Financial Conduct Authority to act as a Primary Information Provider in the United Kingdom. Terms and conditions relating to the use and distribution of this information may apply. For further information, please contact rns@lseg.com or visit www.rns.com. RNS may use your IP address to confirm compliance with the terms and conditions, to analyse how you engage with the information contained in this communication, and to share such analysis on an anonymised basis with others as part of our commercial services. For further information about how RNS and the London Stock Exchange use the personal data you provide us, please see our Privacy Policy. END NOASSUFMLEMSEFU