By Gary Duffy

BBC News, Sao Paulo



The gas field is so huge it could in theory make Brazil self-sufficient

The disappearance of four laptops and two hard drives is being treated as a case of industrial espionage.

Brazil's President Luiz Inacio Lula da Silva has referred to the stolen material as a "state secret".

The investigation into this mysterious and high-profile theft, which happened late last month, is continuing.

The laptops and hard drives were stolen as they were being transported from an offshore rig to offices belonging to Petrobras.

Espionage theory

Police were working on a theory that the crime was industrial espionage, but they have now said they are not totally discounting the possibility that it was a common theft, Brazil's TV Globo reported.

Detectives had earlier highlighted that other valuable equipment was left behind by the thieves, but it appears more items were stolen than had been originally mentioned at police briefings, including a printer and a DVD recorder.

President Lula says the theft is a very serious matter

Detectives say there was a flaw in the security surrounding the delivery, and they have been trying to retrace the container's route to establish where and how the robbery took place.

Police now say the stolen material related to a recent significant discovery of gas off the Brazilian coast, near Rio de Janeiro.

Petrobras revealed details of the Jupiter gas field in January, and while the company did not give precise information, the find was hailed at the time as having the potential to make the country self-sufficient in natural gas.

President Lula has described the theft as a serious matter and has referred to the stolen material as a "state secret".

Police have interviewed at least 17 people who came into contact with the information, or who were involved in its transportation.