The U.S. ambassador to Brazil was summoned by authorities Monday to account for fresh allegations that his nation's National Security Agency (NSA) directly spied on President Dilma Rousseff, an official said.
Ambassador Thomas Shannon arrived and left the Foreign Ministry without speaking to reporters, and there was no comment from the Brazilian side, even as Rousseff met separately with top ministers to discuss the case.
"If these facts prove to be true, it would be unacceptable and could be called an attack on our country's sovereignty," Justice Minister Jose Eduardo Cardozo said Monday.
Glenn Greenwald, a Guardian newspaper columnist who obtained secret files from NSA leaker Edward Snowden, has told Globo television that the agency snooped on the communications of Rousseff.
The June 2012 document "doesn't include any of Dilma's specific intercepted messages, the way it does for Nieto,'' Greenwald told the Associated Press news agency in an email. Mexican President Enrique Pena Nieto's communications were also being monitored by the NSA even before he was elected in July, 2012, it has been alleged.
Greenwald continued: "But it is clear in several ways that her communications were intercepted, including the use of DNI Presenter, which is a program used by NSA to open and read emails and online chats.''
U.S. targeting mapped out the aides with whom Rousseff communicated and tracked patterns of how those aides communicated with one another and also with third parties, the documents reportedly show.
Calls to Rousseff's office and a spokeswoman were not answered. Messages sent to a spokesman for Pena Nieto were not immediately returned.
Sen. Ricardo Ferraco, head of the Brazilian Senate's foreign relations committee, said lawmakers already had decided to formally investigate the U.S. program's focus on Brazil because of earlier revelations that the country was a top target of the NSA spying in the region, and that the probe would likely start this week.
"I feel a mixture of amazement and indignation. It seems like there are no limits. When the phone of the president of the republic is monitored, it's hard to imagine what else might be happening," Ferraco told reporters in Brasilia.
"It's unacceptable that in a country like ours, where there is absolutely no climate of terrorism, that there is this type of spying."
Dean Chaves, spokesman for the U.S. Embassy in Brazil's capital, said in an emailed response that U.S. officials wouldn't comment "on every specific alleged intelligence activity."
But he said, "We value our relationship with Brazil, understand that they have valid concerns about these disclosures, and we will continue to engage with the Brazilian government in an effort to address those concerns."
In July, Greenwald co-wrote articles in Globo that said documents leaked by Snowden indicate Brazil was the largest target in Latin America for the NSA program, which collected data on billions of emails and calls flowing through Brazil.
The Brazilian government denounced the NSA activities outlined in the earlier reports.
Greenwald began writing stories based on material leaked by Snowden in May, mostly for the Guardian.
Before news of the NSA program broke, the White House announced that Rousseff would be honored with a state dinner in October during a trip to the U.S., the only such full state dinner scheduled this year for a foreign leader. The move highlighted the U.S. desire to build on improved relations since Rousseff took the presidency on Jan. 1, 2011.
Rousseff's office said last week that there were no plans to scrap the state dinner because of the NSA program.
Al Jazeera and wire services