By Gary Duffy
BBC News, Sao Paulo
A huge natural gas field has been found a short distance off Rio de Janeiro's coastline, Petrobras, Brazil's state-controlled oil company, says.
Recent finds could turn Brazil into a leading global energy supplier
The company believes the new field, Jupiter, could match the recently discovered Tupi oil field in size.
Tupi is thought to be one of the largest fields discovered in the past 20 years.
But Petrobras officials say further work needs to be done to establish Jupiter's exact dimensions.
The new field is located just 37km (23 miles) from Tupi, some 5,100m (5,600 yards) below the surface of the Atlantic Ocean, around 290km from Rio de Janeiro, Petrobras says.
While not providing any specific details on the size of the new reserve, Petrobras said "its structure could have dimensions similar to Tupi".
Petrobras estimates Tupi contains between five and eight billion barrels of light oil.
When the oil field's discovery was announced last November, the Brazilian government said Tupi could turn the country into one of the World's major oil suppliers.
Analysts were more cautious, pointing out the difficulty of extracting Tupi's oil from beneath deep layers of rock and salt.
Petrobras, though, is a world leader in deep water oil production, and the find was hailed as a major discovery for Latin America's largest country.
The discovery was made by a consortium made up of Petrobras - which has an 80% stake in the find - and Portugal's Galp Energies.
A number of surveys will now have to be carried out to try to establish the scale of the new field.
Brazil's government has recently been forced to deny there was a risk of energy shortages caused by drought at hydroelectric plants which are the country's main source of energy.
It currently relies on Bolivia for much of its natural gas.