Operating profits soared 94% at South America-based oil and gas explorer and producer Amerisur Resources in the first half of the year. Revenue for the period grew from to $6.6m (2010 H1: $4.5m) leading to operating profits of $1.8m. Pre-tax profit more than doubled on a like-for-like basis from $915,000 to $2m. Chairman Giles Clarke said: "We continue to make good progress in both Colombia and Paraguay. We are eagerly awaiting approval from the Ministry of Environment, Housing and Territorial Development so we can commence our significant drilling programme on the Platanillo Block in Columbia. This remains our priority." An unprecedented increase in activity in Colombia and structural changes due to the policies of the new government have delayed this relatively process.After increasing reserves at the Plantanillo block 2P to 3.6m barrels, the company has reached a commercial agreement with Reto Petroleum's Columbian branch to work together to develop the Fenix block. "The agreement with Reto will enable us to make swifter progress on Fenix, and in August we held a successful meeting with the Paraguayan Government and remain confident in the prospects for the San Pedro Block. Therefore we are excited about the prospects for our blocks in the months ahead and look forward to updating shareholders on this, the company said."Cash for the period decreased slightly from $0.26m to $0.18m. The share price rose 5.36% to 14.75p by 12:48.NR