Tethys Petroleum Announces the Successful Closing of US$100 Million Public Offering

October 20, 2010

Toronto, Canada, October 20, 2010 – Tethys Petroleum Limited (“Tethys” or the “Company”) (TSX: TPL) announced today that it has completed its public offering of 70,600,000 Ordinary Shares for gross proceeds of US$100 million (the “Offering”). The Ordinary Shares were sold at a price of US$1.417 (C$1.45) each. The net proceeds of the offering are intended to be used by Tethys to fund work on the Company’s existing properties in Central Asia.

Fraser Mackenzie Limited, Renaissance Capital and Quam Capital acted as joint lead managers for the offering in a syndicate of agents that includes FirstEnergy Capital Corp. The offering was conducted in the provinces of British Columbia, Alberta and Ontario, Canada through Fraser Mackenzie Limited, and FirstEnergy Capital Corp., and Renaissance Capital and Quam Capital acted as special selling agents for the purpose of procuring subscribers in certain jurisdictions outside of Canada, where each such selling agent is qualified to carry on business.

One of the subscribers under the offering is a related party of the Company within the meaning of applicable Canadian securities laws. Additional information relating to the interest of the related party in the public offering is contained in a material change report to be filed in accordance with Canadian securities law on October 20, 2010. The offering was completed in fewer than 21 days from the date of the October 5, 2010 Press Release in respect of the offering to ensure the availability of the proceeds of the offering on a timely basis.

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 news release does not constitute an offer to sell or a solicitation of an offer to buy any of the securities described herein. Any such solicitation or offer may only be made in accordance with applicable laws. The securities have not been and will not be registered under the United States Securities Act of 1933, as amended (the “U.S. Securities Act”), or any state securities laws and may not be offered or sold within the United States or to United States Persons unless registered under the U.S. Securities Act and applicable state securities laws or an exemption from such registration is available.

This press release contains “forward-looking information” which may include, but is not limited to, statements with respect to the anticipated use of the net proceeds of the Offering. Such forward-looking statements reflect our current views with respect to future events and are subject to certain risks, uncertainties and assumptions, including the risk that the proceeds may not be sufficient for the purposes stated in the prospectus dated October 12, 2010. The intended use of the net proceeds of the Offering by Tethys may change if the board of directors of Tethys determines that it would be in the best interests of Tethys to deploy the proceeds for some other purpose 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 prospectus dated October 12, 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 Asia-Pacific

Quam IR

Anita Wan Associate Director Office phone/fax + (852) 2217-2999 anita.wan@quamgroup.com