AMER.L Regulatory News (AMER)

23rd November 2011

Amerisur Resources PLC

("Amerisur" or the "Company")

Platanillo (Colombia) Update

Amerisur Resources, the oil and gas producer and explorer focused on South America, is pleased to announce that the Ministry of Environment and Sustainable Development (Ministerio de Ambiente y Desarrollo Sostenible ("MADS"), previously Ministry of Environment, Housing and Territorial Development ("MAVDT")) has granted the Company a modification to its Global Environmental Licence, over an increased area of 4,480 hectares (previously 935 hectares) following the Company's request in January 2011 to modify and extend the licence to encompass additional prospectivity. As a result, the initial six well development programme in Platanillo will commence over both the original and newer southern areas of the licence early in the New Year. The current Platanillo 2P reserve base is 3.6MMBO (Source: Petrotech Engineering Ltd) and this initial drilling campaign is targeting additional estimated prospective resources of approximately 30 MMBO.

The Company has contracted a Drilling Superintendent who has extensive experience in Colombia and the Putumayo basin to lead the drilling programme. All preparations have been made for the drilling, together with the purchase of significant amounts of long-lead items such as casing, tubing and wellhead equipment. During the interim period the Company has refined the drilling programme and civil work designs to enhance efficiency.

Civil works, which include approximately 8 km of new roads to the south, 4 km of new roads to the north, raised drilling locations and the construction of a 15 metre, 80 Tonne capacity bridge will be initiated immediately and it is anticipated that the first well will be spudded in Q1 2012 depending upon weather conditions. The enhanced well plan indicates the first well will be logged and ready to test within 30 days. Further wells, either directionally drilled from the same pad or from other locations will then follow consecutively. The Company has secured reception and transport facilities for initial production rates up to 5,000 BOPD within nearby regional infrastructure facilities.

Giles Clarke, Chairman commented:

"Whilst the delays caused bythe unprecedented increase in activity in Colombia and structural changes within MADS have been a frustration, we have used the time wisely to make more efficient our drilling programme and to put in place the necessary infrastructure agreements to facilitate high and continuous production rates.

"The drilling, which is targeting prospective resources of 30 MMBO, will commence in Q1 2012 and we anticipate high quality oil production rates of circa 2,000 BOPD around midyear 2012 and 5,000 BOPD at the end of the year from the Platanillo field.

We have been most encouraged by President Santos's impressive speech on Monday of this week in London during his official visit to the UK, in which he set out his government's long term strategy and expressed his strong and continuing support for foreign direct investors in Colombia like Amerisur."

John Wardle, CEO said:

"The grant of the modification to our Global Environmental Licence for the exploitation of the Platanillo field has approved Amerisur Resources' plan for the required infrastructure works, 11 additional drilling platforms with up to a further 55 wells, currently anticipated to be required over the remaining 22 years of this phase of the Platanillo contract. I am grateful for the Colombian government's support for our projects and can confirm the Company's complete commitment to the highest standards of environmental management and to sustainable operations during this important development campaign."

-Ends-

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Notes to editors

During H1 2012 production from Platanillo was 62,000 BO, which generated US$6.6MM in revenue. Petrotech Engineering Ltd has published an independent reserves report which showed that certified 2P reserves at Platanillo were 3.6MMBO. The next drilling campaign is targeting additional estimated prospective resources of 30 MMBO. These reserves were calculated in accordance with the requirements of the National Hydrocarbons Agency (ANH).