Celtic Sea Well

Island Oil and Gas PLC
06 June 2006


6 June 2006


               ISLANDS FIRST CELTIC SEA WELL REACHES TARGET DEPTH
                               AND ENCOUNTERS GAS
                                        
Island Oil & Gas plc ('Island' or the 'Company') today announces that the first
well of its 2006 and 2007 drilling programmes offshore Ireland, Well 48/23-3 at
Seven Heads West in the Celtic Sea, has been drilled to target depth and has
encountered gas shows.  The Company and its Partners, Marathon Seven Heads
Limited and Sunningdale Oils Ireland Limited, are now evaluating log information
and formalising the details of the planned testing programme that will be
submitted to the Petroleum Affairs Division of the Department of Communications,
Marine and Natural Resources in accordance with the normal procedures for
seeking the necessary approvals and consents to test the well.

Well 48/23-3, which was spudded on 4 May 2006 in a water depth of 341 feet was
drilled to its planned total depth of 3,237 feet TVD ss.  The well has
encountered gas bearing sands, at the prognosed stratigraphic levels.  The
Company will be announcing further details at the conclusion of the planned
testing programme.

Well 48/23-3 is operated by Island and was drilled using the semi-submersible
drilling unit, Petrolia, owned and operated by Petrolia Drilling Limited under
contract to Island.


Enquiries:

Lisa J Newman MCIPR MIRS
Newman Consulting
Tel: [phone]

Notes to Editors:

Island was founded in 2003 and listed on AIM in December 2004.  The Company has
interests in nine Irish offshore licences, (four as operator and two as
technical manager), including one producing gas field.

Island concluded a Sub-Area Equity Interest Assignment Agreement for the Seven
Heads West area with Marathon International Petroleum Hibernia Limited, through
its wholly-owned subsidiary Marathon Seven Heads Limited in February 2006.
Under the Agreement, Island is funding 100% of the cost of the current well,
including testing, in return for increasing its equity interest in the Seven
Heads West, Sub-Area, from 12.5% to 55.75%.  Island has operated the well during
the drilling period but operatorship will revert back to Marathon once drilling
and testing has been completed.






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