Brazil's foreign minister has criticised US surveillance practices, dismissing as unsatisfactory Secretary of State John Kerry's explanation of the wide-ranging collection of data on telephone and electronic communications.
He also described the spying as "a new type of challenge" in Brazil's relationship with the US.
Foreign Minister Antonio Patriota issued the unusual expression of indignation over the National Security Agency's spying programmes on Tuesday while standing next to Kerry at a news conference in Brasilia, the capital, where the secretary of state had stopped on a two-day trip to South America. Resentment has festered in Brazil since revelations of the surveillance practices emerged in July.
They detailed how the agency established a data collection centre in Brasilia and prioritised Brazil, with its vast telecommunications hubs and large population, as among the agency's most spied-upon countries.
Patriota, a former ambassador to the US, said the surveillance practices "cast a shadow of distrust" over bilateral relations and that "listening to explanations doesn't mean accepting the status quo".
Kerry replied: "Brazil is owed answers with respect to those questions, and they will get them. And we will work together very positively to make certain this question - these issues - do not get in the way of all the other things we talked about."
Convincing Brazil that such spying is needed may be an uphill struggle. But the Obama administration knows that without strong ties with Brazil, the US cannot have a satisfactory approach to a range of issues in Latin America, including energy integration, curbs on environmental degradation and the fight against drug trafficking.
Kerry tried to emphasise the positive aspects of relations with Brazil by focusing on subjects like the government's plans to send tens of thousands of Brazilian students to US universities and vigorous bilateral trade, tilted in advantage of the US in the form of an ample surplus.