Platanillo Update

18 March 2013

Amerisur Resources Plc

Platanillo Update

Amerisur Resources Plc ("Amerisur" or the "Company"), the oil and gas producer and explorer focused on South America (LSE: AMER), is pleased to announce an update on its operations in the Platanillo field, Colombia.

·;   Platanillo-1 ST1 sidetrack encountered a 22ft net pay interval in the U sand and produced 530 bopd in a controlled production test

·; Platanillo-10 encountered 68 ft net pay in U and T sands

·; Platanillo Field production currently at 4,700 bopd, constrained by pipeline and export facility availability

·; Total field production capacity estimated at 6,400 bopd

·; Alea-1 ST1 sidetrack to commence shortly

The well Platanillo-10, the sixth well of the current Platanillo drilling programme and located on platform 5 South (5S) was deviated approximately 1,865ft north east of platform 5S. The well encountered an interval of 80ft Gross, 68ft net indicated pay in the U sand and T sand. As predicted by the geophysical model, the N sand was not well developed at this point. It is expected the well will be completed and placed on production during March.

Platanillo-1, drilled in 2007, and not tested by the previous operator, ECOPETROL, was re-entered and was sidetracked to a location approximately 2,485ft to the east. The objective of this sidetrack was to further delineate the oil columns in the Platanillo reservoirs and potentially to provide a water injection facility for the field. This well, named Platanillo-1 ST1, encountered a 22ft net pay interval in the U sands, of which 7ft was perforated, producing 530 BOPD on test. The well has now been placed on commercial production.

Platanillo field production continues to be constrained by local conditions. The Company has been active in developing new alternatives for oil delivery, and expects those options to allow a continued growth in production over the coming months.

The Serinco D-10 drilling rig is currently being moved from the Platanillo-1 ST1 location to the Alea-1 location. It is planned to re-enter and sidetrack that well to a structurally more favourable position for oil production.

Rig Latco-01 continues operations on Platanillo-10, after which it will be skidded to drill well Platanillo-11, the seventh new well of the current drilling programme on the same platform.

Dr. John Wardle, Chief Executive commented:

"I am very excited by the result of the Platanillo-1 ST1 sidetrack. To encounter producible oil at that position in the structure augurs well for the size of the eventual recoverable resource in the Platanillo field. Additionally, this great result has significantly de-risked the northern section of Platanillo. Based on our 3D seismic and this well data I am confident we will develop significant reserves volumes in the northern part of the block. Platanillo-10 continues our unbroken 100% commercial success record, with a very good oil column in excellent quality reservoirs and exactly in line with our geological model. I look forward to further success in Platanillo, as we continue to build up our exploration effort into our adjoining Put-12 acreage."

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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