Full details of the deposit will be available within a year, he told media at an opening ceremony for gas stations that Petrobras had bought from Shell.

Petrobras has been exploring close to the town of Recetor, in the eastern department of Casanare, where Colombia's largest crude deposits have been found. The Brazilian company has drilled to a depth of 7,000 meters, but needs to drill to 19,000 meters to confirm the presence of petrol.

"Data shows a good chance of finding petrol," Abrahao said, adding that the company would invest 70 million U.S. dollars in the project.

Colombia's energy and mines minister, Hernan Martinez, called for prudence, saying that there remained many tests to be done before the find could be confirmed as crude, because it could also be gas or water.

"There may be several months of delay between drilling and proof," he added.

Petrobras and the mainly state owned Colombian Petrol Company (Ecopetrol) signed an agreement to promote biofuels in Colombia on Tuesday.