"The decision was communicated in a meeting Tuesday with incoming defense minister (Walter Souza) Braga Netto and outgoing minister Fernando Azevedo," the defense ministry said in a brief statement that did not give a reason for their departure.

Some Brazilian media reported the trio had resigned in protest at Bolsonaro's surprise decision Monday to replace Azevedo.

"For the first time in history, the commanders of all three branches of the armed forces presented their joint resignation in disagreement with the president," said newspaper Folha de Sao Paulo.

Bolsonaro gave his embattled administration a thorough shake-up Monday, replacing the foreign, justice and defense ministers as well as his chief of staff, attorney general and government secretary.

Last week, he also replaced former health minister Eduardo Pazuello, an army general with no medical experience, with cardiologist Marcelo Queiroga, his fourth health minister of the pandemic.

Bolsonaro is facing mounting pressure over a deadly surge of Covid-19 in Brazil, where the average daily death toll has nearly quadrupled since the start of the year to more than 2,600, pushing hospitals to breaking point.

The president, who comes up for re-election in October 2022, facing growing dissatisfaction -- including from key allies in Congress and the business sector -- over his handling of a pandemic that has now claimed nearly 314,000 lives in Brazil, the second-highest death toll worldwide, after the United States.