A man walks on the beach past an offshore oil drilling rig

Brazilian President Dilma Rousseff on Tuesday celebrated the success of national deep-sea oil exploration in so-called pre-salt reserves of the South Atlantic.
Rousseff presided over a ceremony marking state-run oil and gas giant Petrobras reaching a production milestone of 500,000 barrels a day at pre-salt reserves.
Petrobras is a pioneer in oil exploration in ultra-deep waters below a layer of salt, and the country has extensive offshore pre-salt oil reserves.
Petrobras' achievement proves pre-salt oil is a "tangible resource" and benefit for the Brazilian population, said Rousseff.
The president also defended the company against recent accusations of irregularities in a deal to purchase an oil refinery in Pasadena, Texas. At the time of the acquisition, Rousseff headed Petrobras' board.
The questionable purchase was an "isolated incident" that should not tarnish the company's image, she said.
In 2006, Petrobras signed the Pasadena refinery deal for which critics say it paid 20 times the market value. The deal prompted the Senate to open an inquiry into alleged corruption and mismanagement at Petrobras with Rousseff's prospect to win reelection in October at stake.