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DUSHANBE, TAJIKISTAN--(Marketwire - May 31, 2010) - Tethys Petroleum Limited ("Tethys" or the "Company") (TSX:TPL) today announced that drilling operations had commenced on the East Komsomolsk KOM201 appraisal well.

The KOM201 well is designed to appraise the eastern portion of the Komsomolsk gas field, which lies beneath the northern part of Dushanbe, the capital city of Tajikistan. It is being drilled by Tethys' ZJ30 rig "Tykhe", and is a deviated well intended to intersect several reservoir intervals but primarily the Jurassic carbonate reservoir. The planned total depth of the well is 2,480 metres with a horizontal displacement to the south. It is expected that drilling operations will be completed within approximately 60 days. This well is being drilled to the north east of the KOM200 well that achieved a stable flow of gas but requires further work to properly test the well following the drillstring becoming stuck. Tethys plans to recommence work on KOM200 after the completion of KOM201.

An independent reserve and resources report effective December 31, 2009 gave for the Komsomolsk field gross 3P reserves of some 2.9 billion cubic feet (Bcf) of natural gas plus mid-case gross unrisked contingent and prospective resources of 17.3 and 57.7 Bcf respectively. Any success on this well would most likely move some of the resources into the reserves category. This field lies under Dushanbe and has existing pipeline infrastructure in place. The surface location of the KOM201 well is close to the large "Tojikcement" cement plant, one of the significant gas consumers in the area. Tethys believes that current natural gas prices in the Dushanbe area are approximately US$6.17 per thousand cubic feet (US$218 per thousand cubic metres).

Tethys is focused on oil and gas exploration and production activities in Central Asia with activities currently in the Republics of Kazakhstan, Tajikistan and Uzbekistan. This highly prolific oil and gas area is rapidly developing and Tethys believes that significant potential exists in both exploration and in discovered deposits.

This press release contains "forward-looking information" which may include, but is not limited to, statements with respect to our operations. Such forward-looking statements reflect our current views with respect to future events and are subject to certain risks, uncertainties and assumptions, including technical and geologic risks and risks relating to regulatory approvals and of sufficiency of the proceeds for the purposes contemplated. See the description of risks and uncertainties and underlying factors and assumptions relevant to the offering and "forward looking information" contained herein and to the Company's business, including its exploration and development activities, contained in the Annual Information Form dated March 31, 2010 (which are incorporated herein by reference). The "forward looking statements" contained herein speak only as of the date of this press release and, unless required by applicable law, the Company undertakes no obligation to publicly update or revise such information, whether as a result of new information, future events or otherwise.