Reserves Update

28 March 2012

Amerisur Resources Plc ("Amerisur" or the "Company")

Reserves Update

Amerisur Resources Plc, the oil and gas producer and explorer focused on South America, is pleased to report an update to the certified reserves for the Platanillo Field, Colombia.

Following receipt of an independent reserves report as at 31 December 2011 undertaken by Petrotech Engineering Ltd using the standards set by the Oil and Gas Reserves Committee of the Society of Petroleum Engineers, certified 2P (Proven and Probable) reserves have increased by 114% to 7.7 MMBO. These 2P reserves have been evaluated by Petrotech as representing a Net Present Value ("NPV") of US$401m undiscounted and a 10% discounted NPV of $204m. Petrotech also calculated 3P (Proven, Probable and Possible) reserves at 10.6 MMBO. In addition, the report certifies a further 3 (best case) to 5.2 (high case) MMBO from the Lower U and N formations as unrisked prospective resources.

John Wardle, CEO said:

"We continue our strategy of de-risking the asset base at Platanillo and are very pleased to announce this significant reserve upgrade. We are on track to deliver upon our six well 2012 drilling programme in Platanillo."

Competent person: Technical information in this announcement has been reviewed by John Wardle Ph.D., the Company's Chief Executive. John Wardle has 27 years' experience in the industry, having worked for BP, Britoil, Emerald Energy and Pebercan, and is a trained drilling engineer.

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