Brazil's outgoing President Luiz Inacio Lula da Silva justified the spending, financed by the country's commodity exports bonanza, as part of a strategy to secure Brazil's regional pre-eminence.
Brazil is campaigning for permanent membership of the U.N. Security Council as part of its strategy to assert its leadership on the continent. The initiative has already led to neighboring countries instigating programs to rival Brazil's military and nuclear expansion plans. Argentina announced a revival of its nuclear development program this month.
Officials said the navy was working on plans to build or incorporate in its fleet at least 26 submarines, six of them fueled by nuclear power. Last year Brazil signed strategic cooperation contracts with France that includes joint production of nuclear-powered submarines.
Despite chronic poverty and poor urban development for most of its population, Brazil boasts a highly developed and sophisticated minority community of highly qualified scientists and technicians active in the country's defense industry.
Lula revived defense manufacturing that was left moribund when the military was replaced by democratic rule in the 1980s and after setbacks received when the Iraq-Iran war's end decimated Brazil's arms industry.
The new procurement plan is likely to be completed in three decades and, once implemented, officials said, it will make Brazil's navy the most dissuasive of maritime military forces in South America.
Brazil hasn't spelled out the source of the threat it faces, except to say it feels justified in building up its defenses to protect newly discovered offshore hydrocarbon resources.
About $2 billion of government spending has already been set aside for the naval expansion.
What remains unclear is if President-elect Dilma Rousseff agrees with Lula on the vast military spending while Brazil faces huge problems of poverty, narcotics abuse and urban violence.
Officials said Brazil's home-grown manufacturers will build the conventional submarines in two batches with the first batch of 15 new ones likely to include some vessels modeled after the French Scorpion class submersible. The Brazilian version is likely to be larger than the French vessel, officials said.
Brazil also plans to refurbish and recommission submersibles it commissioned earlier, including the Tupi class based on German technology and Tikuna class developed by the Brazilian navy.
Alongside the naval development program, Brazil has announced ambitious plans for uranium enrichment, a program the United States tried to control when it first started in the 1980s.
Brazil, active in nuclear research since the 1930s, conducted a covert nuclear weapons program under military dictatorship in response to Argentina's nuclear program, also run under military rule.
Early Brazilian initiatives led to a limited reprocessing capability, opposed by successive U.S. administrations, a missile program, a uranium mining and processing industry and fuel processing on facilities.
Defiant Brazil bought nuclear materials and equipment from West Germany in the 1980s. Brazil has two nuclear power plants in operation and one under construction.
The inclusion of nuclear powered submarines means Brazil will redouble its uranium enrichment effort. Officials are confident Brazil can produce up to 40 tons of enriched uranium a year.
The naval and nuclear developments are meant to run side by side as part of an overall defense strategy.