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 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.
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