Increase in Resources Estimates in Shanagarry

10 April 2013

Fastnet Oil & Gas Plc announces

Significant Increase in Independent Resources Estimates in its North Celtic Sea

Licensing Option 12/5 ("Shanagarry")

 Highlights of Independent Resources Estimates:

§ 123 sq. km. structure updip from oil and gas bearing intervals in the 49/19-1 Shanagarry structure

§ Multiple reservoir targets consistent with analogous tested and producing intervals in Barryroe and Kinsale oil and gas fields

§ Aggregated unrisked gross P50 Best Case Prospective resources of 1.298 billion barrels of oil in-place and 1.342 TCF of gas in-place

§ Geological Chances of Success vary from 12 to 14% for oil reservoirs and 5 to 10% for gas reservoirs

Fastnet Oil & Gas plc ("Fastnet" or the "Company") (AIM: FAST, ESM: FOI) the E&P company focused on near term exploration acreage in Morocco and the Celtic Sea, is pleased to announce that an independent assessment of the Company's prospective resources on licensing option 12/5 ("Shanagarry" or the "Licensing Option") has been completed by SLR Consulting. Fastnet farmed-into thelicence on 14 November 2012 and now operates and holds an 82.35% working interest in Shanagarry following ministerial consent received on 8th April 2013. The independent assessment was carried out in accordance with generally accepted international standards. The following table has been prepared by Fastnet for the convenience of readers to summarise prospective hydrocarbon resources in the 49/19-1 Shanagarry structure ("49/19-1") and the associated geological chance of success ("GCoS").

UNRISKED GROSS PROSPECTIVE RESOURCES (49/19-1 SHANAGARRY STRUCTURE) AS AT 9 APRIL 2013

*See Note 4 in the "Notes to Editors" section below.

49/19-1 covers an area of 123 sq. km., making it one of the more significant hydrocarbon-bearing structures in the North Celtic Sea. Four hydrocarbon-bearing intervals were encountered in 49/19-1, whilst the Upper Wealden may potentially be hydrocarbon-bearing updip from the well based on offset gas discoveries at Ardmore and Old Head.

Purbeck and Lower Wealden reservoirs, oil-bearing in 49/19-1, form the lowest risked reservoir objectives. STOIP estimates are higher than the published P50 estimates for the Middle and Basal Wealden reservoir intervals for Barryroe (April 2013).

The Kimmeridgian/Portlandian overpressured "tight gas" and Middle/Upper Jurassic gas-bearing intervals have also been evaluated. Subject to a scoping well design to address the issue of collecting the data required to model the potential for sustainable commercial flow rates, the "tight gas" potential prospective resources could be a viable add-on to a development of the conventional oil and gas prospective resources in the 49/19-1 Shanagarry structure, as a result of economies of scale should the area become a "hub" for appraisal and development. In such a case a number of currently stranded gas assets could also be developed as satellite tie-backs to the hub.

The Independent Technical Evaluation Report on the Shanagarry Licensing Option is available to download on the Fastnet website at www.fastnetoilandgas.com .

Commenting, Paul Griffiths, MD of Fastnet, said:

"SLR Consulting's independent assessment confirms the significant resource potential of Shanagarry. 49/19-1 was drilled by Marathon in 1984 at a time of low oil and gas prices and prior to the discovery and appraisal of Barryroe (Basal Cretaceous oil) and the Dragon Field in Cardigan Bay (Basal Upper Jurassic gas and condensate).It covers an area of 123 sq. km. and is therefore comparable in size to the Kinsale gas field and Barryroe oil field structures. Geological similarities with both Deep Kinsale and Barryroe have now been independently confirmed by SLR Consulting. The addition of running room represented by our Deep Kinsale and 49/19-1 will be an additional positive factor in a potential farm-out or similar transaction. Indeed the prospective resources have now reached a critical threshold for a new entrant wishing to develop an appraisal and development hub in the central Celtic Sea adjacent to the Kinsale gas-gathering infrastructure.

"3D seismic over Deep Kinsale may mature prospects for drilling as early as 2014 as part of a multi-well drilling programme with other Celtic Sea operators. We believe the Celtic Sea is set to be transformed over the next 12 months as it once again becomes Ireland's foremost oil and gas basin. Fastnet's 3D seismic programmes and farm-out activity places the Company in a unique position in the Celtic Sea to provide running room for international oil companies seeking to add offshore Ireland to their "core area" portfolios."

For further information please contact:

Notes to editors

Fastnet Oil & Gas plc is an independent oil and gas exploration company that focuses on identifying early stage exploration and appraisal opportunities in Offshore Ireland and Africa. It is quoted on the AIM market of the London Stock Exchange and the Enterprise Securities Market ("ESM") of the Irish Stock Exchange. Fastnet's aim is to assemble a portfolio of high impact conventional oil and gas assets that will deliver sustainable growth and value for the Company. Its immediate focus is on implementing its Offshore Ireland and Africa strategies where it has been awarded four offshore licensing options in the Celtic Sea (Molly Malone Basin, Shanagarry, 49/13 and Mizzen Basin) and acquired a material interest in the highly prospective Foum Assaka permit Offshore Morocco. In addition, Fastnet will continue to pursue new conventional oil and gas opportunities in Africa where the Directors and Advisory Board also have extensive knowledge, contacts and experience of creating value.

 Notes:

1. Prospects are features that are sufficiently well defined, on the basis of geological and geophysical data, to the point where they are considered viable drilling targets.

2. "Gross Unrisked Prospective Resources" are 100% of the volumes estimated to be in-place in a prospective structure.

3. The GCoS reported here represents an indicative estimate of the probability that drilling this Prospect would result in a discovery, which would warrant the re-classification of that volume as a "Contingent Resource". The GCoS value for Contingent Resource is, by definition, unity. These GCoS values have not been arithmetically applied to the designated volumes within this assessment. Thus the volumes are "Unrisked".

4. It is inappropriate to aggregate Prospective Resources without due consideration of the different levels of risk associated with each Prospect and the potential dependencies between them.

5. The above table represents the expected outcomes for an oil and gas discovery based on the nearest analogues being the undeveloped Barryroe oil field and the undeveloped Helvick oil field, 50/6-1 oil discovery and Dragon gas field.