Tethys Petroleum: Drilling Update

May 17, 2010

BOZOI, KAZAKHSTAN AND DUSHANBE, TAJIKSTAN, May 17, 2010 (MARKETWIRE via COMTEX) –Tethys Petroleum Limited (“Tethys” or the “Company”) (TSX: TPL) today gave drilling updates on its wells in Kazakhstan and Tajikistan.

Kazakhstan

The AKD02 appraisal well to the AKD01 (Doris) oil discovery was spudded on April 1, 2010. The drilling of this well is on schedule and is currently at a depth of 1,509 meters having successfully run 245 mm casing. It is expected to have initial results from this well by the end of June 2010.

The AKD02 appraisal well is the first appraisal well to the AKD01 oil discovery which flowed at a rate in excess of 6,800 barrels of oil per day and will provide valuable further information on the size of the new oil field. It is planned to drill at least two appraisal wells on the Doris oil discovery to evaluate and establish the size and potential of the discovery and also to provide the necessary data to obtain a production contract. These wells will be extensively evaluated with coring, detailed geophysical logging and testing. A further appraisal well may also be drilled if deemed necessary after evaluating the results of the first two wells.

In addition to the appraisal programme Tethys plans to carry out a 3D seismic survey over the Doris discovery and shoot additional targeted 2D seismic lines to firm up further potential in the area. The seismic contract has been awarded and the programme is expected to commence in mid June 2010 and will be targeted to provide additional data for the second appraisal well which should commence drilling in the summer.

In addition to the Doris oil discovery Tethys has identified several other exploration prospects in the area which appear similar to Doris and now that a hydrocarbon system has been proven at the deeper levels the risk on these prospects is reduced significantly. Tethys’ ZJ70 rig “Telesto” is fully rigged up and ready to commence drilling on a prospect located to the south-west of Doris to drill the AKD03 exploration well (“Dione”) with operations expected to commence before the end of this month. This well is planned to target both the Cretaceous and Jurassic intervals where oil has been flowed in the Doris oil discovery, and also the deeper Triassic and Permo-Carboniferous intervals that are believed to have further potential. Further exploration drilling on the Akkulka block and on large surrounding Kul-Bas block is then planned.

Tajikistan

The Komsomolsk KOM200 gas appraisal well reached the top of the Jurassic sequence and hydrocarbons were indicated both whilst drilling and on electric logs, and an open hole flowback test was carried out which resulted in a stable gas flow, albeit accompanied by water from water bearing zones in the large open hole section. However the drillstring then became stuck, probably due to differential pressures, and to date the Company has not been successful in retrieving the string. Work is now on hold for KOM200 but has commenced towards the drilling of a new well (KOM201) to the north east of KOM200. It is planned to come back to KOM200 once specialist equipment has arrived in Tajikistan and KOM201 is completed.

Tethys’ ZJ30 drilling rig “Tykhe” has now been moved to the KOM201 location and it is expected that drilling of this well will commence towards the end of May. The surface location of KOM201 is located to the NE of the surface location of KOM200 close to the Tojikcement plant, one of the largest cement plants in the region and a significant gas consumer. The well will be drilled as a directional well with its planned target being to the SSE of the surface location under the northern suburbs of the capital city of Dushanbe.

Work on the East Olimtoi exploration well EOL09 is currently suspended whilst additional equipment is mobilised to Tajikistan to continue drilling to the target zone which is some 1,000 metres from the current depth of 2,941 metres. The Company is continuing with its seismic survey programme in Tajikistan with the aim of identifying other targets and is looking at other drilling possibilities. The Company is actively seeking partners in certain projects, preferably strategic partners, and has begun a farm-out process with respect to certain of its Tajik assets having held a data room for interested parties.

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 the 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.

Contacts: Tethys Petroleum Limited Sabin Rossi Vice President Investor Relations +1 416 572 2065 +1 416 572 2201 (FAX) info@tethyspetroleum.com www.tethyspetroleum.com In Kazakhstan PG Communications Ardak Akanov, Managing Director Office phone/fax: +7 (727) 272 8867, +7 (727) 272 8237, +7 (727) 272 7745 development@pressclub.kz In Asia-Pacific Quam IR Anita Wan, Associate Director + (852) 2217-2999 anita.wan@quamgroup.com
SOURCE: Tethys Petroleum Limited

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