AMER.L Regulatory News (AMER)

22nd March 2010

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

Operations Update Isabel-1

Amerisur Resources Plc, the oil and gas producer and explorer focused on South America, is pleased to provide the following update on operations in the Fenix Block, Colombia.

The 8.1/2" Pilot Hole of Isabel-1 was drilled to a final depth of 1,365ft. The hole has been logged and plugged back to allow the deviated part of the well to be drilled directionally from higher in the pilot wellbore.

The results up to now have been encouraging and in line with the Company´s expectations. The top sand of the Esmeraldas-La Paz formation was encountered at 1,002 ft Wire Line Depth, confirming the pre-drill prognosis. An apparent net thickness of approximately 280 ft of good quality sandstones was encountered with strong shows of gas, oil, oil on cuttings samples and also free oil visible on the shale shaker throughout this section. The mud weight used through this section was 9.2 ppg.

The well is currently being directionally drilled to position the well bore in the most advantageous position to evaluate the sands.

Final target depth is estimated at 1,850ft measured depth with an inclination of up to approximately 56 degrees from the vertical.

 John Wardle, CEO, said:

"I am pleased with the good progress and encouraging indications at Isabel, and look forward to updating shareholders as the work proceeds."

Competent person: Technical information in this announcement has been reviewed by John Wardle Ph.D., the Company's Chief Executive. John Wardle has 25 years experience in the industry, having worked for BP, Britoil, Emerald Energy and Pebercan, and is a trained drilling engineer.

ENQUIRIES:

Notes to editors

The Fenix Contract is an Exploration and Production Contract held with the Agencia Nacional de Hidrocarburos of Colombia. The block is located in the Middle Magdalena Valley area of Colombia and covers 24,116 hectares. Nearby oil fields include Bonanza, Provincia and Payoa. The Company holds 100% of the block through its subsidiary companies. Amerisur´s first exploration well on the block, Iguasa-1 was drilled during October and November 2009. The contract is currently in the third exploration phase of 14 months which terminates on 21st April 2011. The exploration commitment for 2011 will be satisfied by the drilling of Isabel-1. The fourth phase of the Fenix Exploration Period has a duration of 14 months and the exploration commitment is the acquisition and processing of 50km of 2D seismic data and geological studies.