Brazil's state-owned energy company Petrobras and its Ecuadorian counterpart Petroecuador signed an agreement on Wednesday, with the aim to exploit the Ishpingo-Tiputini-Tambococha (ITT) oil fields in the Yasuni National Park in Ecuadorian Amazon.

The oil deal, inked by Brazilian President Luiz Inacio Lula da Silva and visiting Ecuadorian President Rafael Correa, is similar to separate agreements signed by the Chilean National Petrol Company (ENAP) and SIPC, a subsidiary of Chinese state-owned company Sinopec, to exploit Ecuador's Amazon region.

Petroecuador will provide environmental, social and economic reports on the field, while the other three companies will present joint plans for evaluating and developing reserves.

ITT contains Block 31, already being exploited by Petrobras, which has invested 461 million U.S. dollars in Ecuador in the last four years. ITT's estimated 1 billion barrels of heavy crude is in the heart of Yasuni, one of Ecuador's most important animal and plant reserves, 320 km north of the Ecuadorian capital of Quito.

Oil exploration in the region has been held back several times by environmental activists.

Petrobras and Petroecuador also signed a memorandum of understanding, aimed at launching a joint research by the Brazilian Agricultural Investigation Agency and Ecuador's Ministry of Agriculture on the technical, economic and legal viability of biofuel production and distribution joint ventures in Ecuador.

At a press conference after the signing ceremony, Lula described Correa, who arrived here on Tuesday evening, as a "friend and colleague."

"We want to face the challenge of transforming the world energy framework together," he said. "Even though we are self-sufficient exporters of petroleum, our nations are determined to promote this new clean and renewable energy revolution."

Lula also asked Correa to expedite Ecuador's change from associate member to full member status of the Southern Common Market (Mercosur), a regional trade bloc made up of Argentina, Brazil, Paraguay, Uruguay and Venezuela.

He also said he would work to reduce Brazilian tariffs on Ecuadorian goods as Ecuadorians have complained of Brazil's large trade surplus with its smaller neighbor.

During Correa's visit, Ecuador and Brazil signed a total of 15 agreements, covering areas of health, social management, finance, labor, petroleum and technology.