As it bids for great power status, Brazil is boosting its naval power in the South Atlantic with an ambitious submarine program to protect its huge deep-water oil reserves and project its growing influence.

The emerging powerhouse already boasts Latin America's largest navy, but its aging fleet, including the Sao Paulo aircraft carrier -- formerly the French Navy's Foch -- nine British-built frigates and five coastal diesel-electric submarines, is in urgent need of modernization.

"The fleet is currently inadequate to carry out its assigned missions" in the South Atlantic, an area Brasilia regards as of high strategic value, Nelson During, chief editor of Brazil's respected defense website DefesaNet, told AFP.

Under the National Defense Strategy unveiled in 2008, the navy was tasked with developing a force to protect the country's huge "sub-salt" oil reserves, the Amazon river basin and its 7,491 kilometers (4,655 miles) of coastline.

The oil fields, located off Brazil's southeast Atlantic coast beneath kilometers of ocean and bedrock, could contain more than 100 billion barrels of high-quality recoverable oil, according to official estimates.

In a speech to the Navy's top brass in June, President Dilma Rousseff stressed that the buildup, including the acquisition of the country's first nuclear-powered submarine, was a key "instrument of deterrence."

Earlier this month admiral Luiz Umberto de Mendonca told a congressional panel that some $117 billion would be needed by 2030 to fund the buildup, including the acquisition of 20 conventional submarines, six nuclear-powered ones and the creation of a second fleet to be based on the northeastern coast.

But During said such plans were "totally unrealistic given the 26 percent cut in this year's 15 billion real ($8 billion dollar) defense budget," adding that the navy only gets a third of that.

"We don't have the money and defense is not a priority in Congress," During added. "There is a feeling that we are a large country at peace with the world, with no external conflicts."

Eric Wertheim, an analyst with the US Naval Institute in Annapolis, said that Brazil, with "a powerful economy and around 200 million people...must be able to defend its deep-water oil fields and protect the Amazon region.

"The country (must) also be ready for an unpredictable future that might include demands like escorting merchant ships that are vulnerable to piracy attacks on the other side of the world," Wertheim, who edits the Naval Institute Guide to Combat Fleets of the World, told AFP.

The recent oil spill from a well operated by a US energy firm off Rio de Janeiro state "showed how unprepared the navy was to deal with such emergencies," he said.

The centerpiece of the naval buildup is the ProSub program, under which France is to supply four diesel-electric submarines and help develop the non-nuclear components of Brazil's first nuclear-powered fast attack submarine.

Except for the first boat, expected to be ready around 2016, all submarines are being built, with French technology transfer, at the Itaguai naval base and shipyard near Rio.

Brazil already has the uranium enrichment technology required for producing nuclear fuel and wants to use it to power the submarine.

But During said that because of repeated delays, the $2.66 billion nuclear submarine was not expected to be completed before 2025.

In addition to its deterrence value, a nuclear sub would give Brazil "status" and add "credibility" to its ambition to become a permanent member of the UN Security Council, he added.

Brazil also "intends to show the flag" in the South Atlantic, in view of its growing trade ties with African countries across the ocean, particularly former Portuguese colonies such as Angola, During said.

Some Brazilian strategists argue that Brazil should become "the dominant naval power in the South Atlantic, without excluding others," he added.

Last year, former defense minister Nelson Jobim raised eyebrows when he described any expanded NATO presence in the South Atlantic as "inappropriate," and some Brazilian lawmakers expressed concern when the United States decided to reactivate its Fourth Fleet in the area in 2008.

But During dismissed those comments "as rhetoric for domestic consumption."