The National Security Agency monitored Brazil's largest state-controlled oil company, Petroleo Brasileiro SA, known as Petrobas, according to classified documents obtained by Edward Snowden.
The news comes via Brazilian television station Globo TV's Fantastico news magazine, just a week after revelations the NSA also kept tabs on Brazilian President Dilma Rousseff.
At last week's G20 meeting in St.Petersburg, Rousseff said her plans for a visit to the U.S. next month were potentially being reconsidered while she waits for assurances from President Barack Obama the spying has not been detrimental to the countries' relationship.
The report also said the NSA tapped Google's private networks, as well as the Society for Worldwide Interbank Financial Telecommunication, which facilitates many of the world's international bank transfers.
National intelligence director James Clapper defended the surveillance, which the slides said were for economic, diplomatic and political reasons, were "not a secret."
Clapper said the information gathering has saved lives and has "found success in disrupting terror networks by following their money as it moves around the globe."
"What we do not do, as we have said many times, is use our foreign intelligence capabilities to steal the trade secrets of foreign companies on behalf of -- or give intelligence we collect to -- US companies to enhance their international competitiveness or increase their bottom line," the statement said.