Brazilian President Dilma Rousseff has called off a state visit to Washington next month in a row over allegations of US espionage.
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 BBC reports.
The allegations were based on documents leaked by fugitive former intelligence contractor Edward Snowden.
President Barack Obama had promised to investigate the incident and 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.
