RIO DE JANEIRO: Brazil and Colombia''s state-controlled oil groups, Petrobras and Ecopetrol, signed a memorandum of understanding Monday to evaluate joint opportunities to do business, Petrobras said in a statement.

The accord opens the way to both firms cooperating on the exploitation of oil fields in both countries, as well as tenders, refining operations, transport, distribution, petrochemical industry and biofuel, the statement said.

The memorandum was signed by the groups'' presidents, Jose Sergio Gabrielli of Petrobras and Javier Gutierrez of Ecopetrol, in Rio de Janeiro.

Petrobras said it had already invested 452 million dollars in Colombia since 2002 and intends to invest another 361 million dollars over the next four years.

Ecopetrol controls 60 percent of Colombia''s oil output and has operations in Brazil, Peru and the United States.