The U.S. government tapped into computer networks of companies including Google and Brazilian state-run oil firm Petroleo Brasileiro SA, according to leaked U.S. documents aired by Globo, Brazil's biggest television network.

A week after it broadcast a report that the U.S. National Security Agency spied on the presidents of Brazil and Mexico, Globo said the agency had also spied on major companies.

At the very least, revelations of U.S. spying on Petrobras are likely to further complicate the tension between the United States and Brazil over allegations that the NSA spied on the private phone calls and e-mails of Brazilian President Dilma Rousseff.

Brazil has demanded a formal apology and Rousseff aides have said the issue could derail a state visit she is due to make to the United States in October.

The tensions led to an impromptu meeting between Rousseff and U.S. President Barack Obama last week at the G20 meeting in Russia. Obama said he would investigate the allegations.

As with its previous report, Globo disclosed the information in coordination with Glenn Greenwald, a U.S. journalist for the Guardian newspaper, who has worked with former NSA analyst Edward Snowden to expose the extent of U.S. spying at home and abroad.

Any spying on Petrobras is sure to raise hackles in Brazil, which has long been suspicious of foreign designs on its abundant natural resources.

U.S. officials, including Obama on a 2011 trip to Brazil and Vice President Joe Biden during a visit in June, have cited the importance of Brazil's big new oil finds and flagged intentions to work closely with the country for future energy needs.

Presented by Adam Justice