The US National Security Agency (NSA) has been accused of intercepting emails and messages from Ms Rousseff, her aides and state oil company, Petrobras.
The allegations were based on documents leaked by fugitive former intelligence contractor Edward Snowden.
President Barack Obama had promised to investigate the incident.
The White House said he had telephoned Ms Rousseff on Monday to discuss the matter.
The allegations of widespread espionage against Brazilian citizens were first published in July by Rio de Janeiro-based journalist Glenn Greenwald, a reporter for the British Guardian newspaper.
Mr Greenwald alleged that the NSA accessed all internet content that Ms Rousseff had visited online. » | Tuesday, September 17, 2013
