In 2007 Ecuador's President Rafael Correa launched an initiative to protect the Yasuni area of the Amazon basin, which boasts one of the planet's richest ranges of wildlife. However, the sources said that decision has been reversed and an announcement on the plan's future is expected late on Thursday. 

One of the government sources said Correa would announce "the necessary steps" to begin exploration in the area, which consists of three untapped oil blocks known collectively as the Ishpingo-Tambococha-Tiputini (ITT) field. 

Presidential spokesman Fernando Alvarado said on Twitter that such exploration could be carried out safely: "Yes one can intervene with environmental responsibility."