The comments came after the UN Security Council passed a US-sponsored resolution aimed at stopping countries with nuclear technology from making atomic bombs.

Brazil has a substantial uranium reserve and even developed the technology for uranium-enrichment. The country recently signed an agreement with France to jointly build a nuclear-powered submarine.

Alencar is not the first Brazilian politician to express concern about the security of the offshore oil deposits, while the challenges of defending the sparsely populated and resource-rich Amazon region are a regular topic of conversation in ruling circles.

Those worries have grown with Washington's decision last year to reactivate the US Navy's 4th Fleet, which patrolled the Western Hemisphere during the World War II era, and with a prospective agreement to allow US military units access to seven bases in Brazil's neighbour Colombia.