President Lula held urgent meetings to discuss the reports
Brazilian intelligence chiefs have been suspended from duty amid allegations that their agency tapped the phones of top officials, politicians and judges.
President Luiz Inacio Lula da Silva ordered that the agency's leadership be removed while an investigation into the reports was carried out.
The accusations surfaced in a news magazine at the weekend, prompting opposition calls for an inquiry.
Wiretaps are common in Brazil, but the latest reports have raised concerns.
Veja magazine alleged that senior figures, including President Lula's chief of staff and the head of the Senate, had had their phones bugged by the intelligence agency, known as Abin.
The magazine published what it said was the transcript of a telephone conversation between the head of the Supreme Court, Gilmar Mendes, and an opposition politician, Demostenes Torres.
The agent, who was said to have provided the transcript, alleged that such illegal phone tapping was common.
Rule of law
President Lula was outraged by the reports, his spokesman said, and held urgent meetings with Mr Mendes and members of Congress.
A statement from the president's office said Abin's director general, Paulo Lacerda, and other top officials were being removed from their posts until an inquiry was completed.
Although it requires authorisation from a judge, phone tapping is common in Brazil, and conversations of businessmen and politicians under police investigation routinely surface in the local media, says the BBC's Gary Duffy in Sao Paulo.
But the latest reports have raised concerns over wiretaps to a new level, our correspondent adds.
"There is a complete lack of control in the state apparatus," Mr Mendes said.
Some opposition politicians demanded a full inquiry, saying the alleged spying was an attack on Brazil's democracy.
"The rule of law has been broken, the credibility of our democratic institutions has been damaged," said Senator Jose Agripino of the DEM Party.