Amerisur to Gain Remaining Interest in Fenix Block

Amerisur, the oil and gas explorer and developer focused on South America, has agreed on the final terms with Petex Offshore for the acquisition of the remaining 16.25% interest in the Fenix block not already controlled by Amerisur.

In addition, as part of the agreement Amerisur will no longer be required to pay Petex Offshore Inc 15% of Amerisur's net profits from the Platanillo block.

The total consideration for the transaction with Petex Offshore will be 18,240,000 new ordinary shares of 0.1p each in Amerisur.

This acquisition, together with the acquisition of Fenix Oil and Gas S.A. announced previously, will confer to Amerisur, via its subsidiary companies, 100% control and economic benefit of the Fenix block. The Fenix block is an exploration stage project and the Platanillo block contains contingent and prospective reserves.

John Wardle, CEO of Amerisur, has an interest in Tracarta Limited, which holds a one third interest in Petex Offshore Inc and therefore the Transaction is deemed to be a related party transaction. The directors, excluding John Wardle, having consulted with their nominated adviser, Blue Oar Securities Plc, consider that the terms of this transaction are fair and reasonable insofar as the Company's shareholders are concerned.

Application has been made for the shares to be admitted to AIM, with trading expected to commence on Dec., 19 2007. Upon admission, the shares will rank pari passu in all respects with the existing ordinary shares of the company.