Platanillo-4 Update

13 August 2012

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

Platanillo-4 Update

Amerisur Resources Plc, the oil and gas producer and explorer focused on South America, is pleased to announce an update on the well Platanillo-4 in the Platanillo Field, Colombia, the second of a planned eight well drilling campaign.

A 30ft section of the logged 75ft gross oil column was perforated in the U formation in order to perform flow and pressure tests. A number of tool failures prevented the test from continuing and the Company has had to source alternative equipment and reconfigure the well. The Company now expects to perform the tests over the next 7 days and results will be announced once they have been analysed.

Following testing, completion and placing on production of Platanillo-4 the Serinco Rig D-10 will be skidded to the third drilling cellar, to drill the third well (Platanillo-5) of our current programme from the same location (Platform 9), deviating the well to an offset of approximately 1,400ft north from the bottom hole location of Platanillo-3. As previously reported, given the positive results of the wells, the Company intends to drill a total of 4 wells from Platform 9 instead of the 3 wells planned previously. The additional well, denominated Platanillo-9 (due to the order in which wells were permitted with the Ministry of Mines and Energy) will be directionally drilled to a location approximately 1,600ft west of Platanillo-3.

ENDS

Competent person: Technical information in this announcement has been reviewed by John Wardle Ph.D., the Company's Chief Executive. John Wardle has 28 years' experience in the industry, having worked for BP, Britoil, Emerald Energy and Pebercan, and is a trained drilling engineer.

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