President Dilma Rousseff has cancelled a trip to Washington by aides preparing for her scheduled visit to the US next month.
Tensions have escalated since Brazil’s Globo TV reported that the National Security Agency was monitoring communications between Ms Rousseff and top aides.
Her office confirmed that the advance team’s trip had been called off, though her trip apparently remains on the schedule.
Ms Rousseff is in Russia for the G20 meeting. Brazilian media report that she will meet President Barack Obama there to discuss the situation.