Azevedo e Silva is the third ministerial appointment that Bolsonaro, himself a former army captain, has drawn from the military, following that of general Augusto Heleno as minister of institutional security, and astronaut and air force pilot Marcos Pontes as minister of science and technology.

Azevedo e Silva entered the army reserves in September before he was controversially named as special advisor to Supreme Court President Dias Toffoli.

That move sparked consternation from those worried about an army general operating at the head of the judiciary.

The military presence in Brazil's Congress grew in October's general election, with 35 former military personnel voted into Congress -- 31 deputies and four senators -- compared to just 18 in the previous parliament.

It has led to concerns in many quarters that Brazil is heading back towards authoritarian rule, evoking painful memories of the brutal 1964-85 military dictatorship under which Bolsonaro served in the army.

But Brazil's army commander-in-chief, general Eduardo Villas Boas, moved to appease fears of military over-representation in politics, insisting that the army remains "apolitical and without a party."

Villas Boas also praised Azevedo e Silva's appointment, adding: "He's experienced and played a key role during the Olympics. It's the best possible choice."

Azevedo e Silva was in charge of the Olympic Public Authority in 2016 when Rio de Janeiro hosted the summer Games.

Like Heleno, he previously headed Brazil's UN peace mission to Haiti, which was launched in 2004.

He trained at the same military academy as Bolsonaro in the 1970s, where Heleno was an instructor, and like the new Brazilian president was also a paratrooper.

He replaces general Joaquim Silva e Luna, who was the first military appointment to the post since the defense ministry was created in 1999.

Bolsonaro has vowed to reduce Brazil's ministries from 29 to 15 and has so far named six ministers, as well as his chief of staff.

He previously announced the merging of the environment and agriculture ministries before backing down under protest from environmentalists.

Concerns over Bolsonaro's intentions are not without foundation.

The new supremo, who will take office on January 1, has spoken openly of his admiration both for the military dictatorship and its use of torture, mostly against left-wing political opponents.

He has also vowed to reduce indigenous land reserves and made a number of racist, misogynist and homophobic statements that the Inter-American Commission for Human Rights president Margarette May Macaulay described on Monday as "clear hate speech."