The Scorpene-class attack submarines are modeled after the original French-Spanish submersibles and their construction follows a 2009 agreement for extensive technology transfer enabling Brazil to replicate French components and plans.
"The merits of this partnership are technology transfer and a strategic alliance that will strengthen and advance the skills of our navy and industrial sector, making it more modern and capable of defending the country," said Brazilian President Dilma Rousseff.
"We seek nuclear propulsion only for defensive, never offensive, purposes."
Rousseff said the submarine construction program was a strategic issue for Brazil and a response to new defense requirements with vast hydrocarbon reserves discovered over the past few years and scattered offshore hundreds of miles from the shore.
Brazil has also set sights on becoming the lead defense manufacturer in South America, supplying neighbors and allies its products on easy financial terms that will guarantee the country diplomatic and political pre-eminence in the region.
The first of the four submarines is to be completed in 2016.
"Brazil is becoming part of a small group of countries which have the knowledge and technology to build submarines," Rousseff said.
"The capacity to produce submarines is a strategy for both defense and economic growth," she added, citing the export potential as Brazil strives to reduce dependence of commodity exports for its main earnings.
The Scorpene-class submarine consists of more than 36,000 components, which will be produced by 30 Brazilian companies, Rousseff said. Brazilian state defense industry estimates the venture will create at least 46,000 jobs. Work on the nuclear submarine project is also in the early stage and it isn't clear how many experts have been deployed for that purpose. Brazil's first nuclear submarine is to enter service in 2023.
Brazil and France signed a $4.25 billion contract for the construction of the four enlarged S-BR diesel-electric submarines, originally designed by French DCN and the Spanish company Navantia and now by DCNS, the brand adopted by the former French Direction Technique des Constructions Navales and the Direction des Constructions Navales.
The Scorpene-class submarine is equipped with six 533-mm torpedo tubes for 18 torpedoes or SM.39 Exocet anti-ship missiles, or 30 mines in place of torpedoes.
It wasn't immediately clear if the S-BR submarine will be equipped with an air-independent propulsion system that allows a submarine to operate without the need to surface or use a snorkel to access atmospheric oxygen.
Rio de Janeiro is host to the 5th World Military Games with more than 5,000 athletes from 111 countries taking part. The event runs through July 24.
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend
Google buys drone maker Titan Aerospace