Hague and London Oil Regulatory News (HNL)

WESSEX EXPLORATION PLC

(AIM: WSX)

New French Guiana Offshore Oil Discovery

Wessex Exploration PLC ("Wessex Exploration" or "the Company") announces that on 9 September 2011 Tullow Oil plc ("Tullow") issued a news release stating that the Zaedyus exploration well (GM-ES-1), offshore French Guiana, has made an oil discovery having encountered 72 metres of net oil pay in two turbidite fans. Results of drilling, wireline logs and samples of reservoir fluids show that the well has encountered good quality reservoir sands on prognosis.

The objective of the Zaedyus well was to test whether the Jubilee-play, successfully established in West Africa, was mirrored on the other side of the Atlantic. This discovery therefore opens a new hydrocarbon basin within which several neighbouring prospects have been mapped. This result also reduces the exploration risk associated with Tullow's prospect inventory offshore French Guiana, Suriname and Guyana. An appraisal programme and extensive follow-up exploration activities will now be considered.

The Zaedyus well is being drilled in the Guyane Maritime licence using the ENSCO 8503 deepwater semi submersible. The well was drilled in water depths of 2,048 metres and has been drilled to a depth of 5,711 metres. Drilling operations will now continue and the well will be deepened to over 6,000 metres to calibrate the deeper geology. The well will then likely be sidetracked to enable cores to be obtained over the reservoir sections.

Tullow (27.5%) operates the Guyane Maritime license and is partnered by Shell (45%), Total (25%) and Northpet (2.5%), a company owned 50% by Northern Petroleum plc and 50% by Wessex Exploration.

Angus McCoss, Tullow's Exploration Director, commented today:

"The discovery at Zaedyus has proved the extension of the Jubilee-play across the Atlantic and made an important new discovery in French Guiana. Tullow has built a commanding and unique acreage position in South America and this result marks the start of a significant and potentially transformational long-term exploration and appraisal campaign in the region."

David Bramhill, Wessex Exploration's Non Executive Chairman, commented today:

"Wessex Exploration is obviously extremely pleased with the results of the French Guiana GM-ES-1 well. The project is being very professionally managed by the operator and the other joint venture partners and we are delighted to be associated with the initial success received to date. At the time of our AIM admission in March 2011 we had high hopes for the well and are delighted to be able to share this success with shareholders."

This announcement has been approved by Frederik Dekker, BSc. (Geology), MA (Geology) FGS, who is a registered professional geologist with the American Association of Petroleum Geologist (AAPG). Mr Dekker is the Managing Director of Wessex Exploration and has over 40 years of experience in the oil industry.