Victims of Brazil’s dictatorship have responded with fury after far-right president Jair Bolsonaro ordered the country’s armed forces to commemorate the anniversary of a 1964 coup which unleashed 21 years of military rule.

Bolsonaro, a former army captain, has frequently praised the regime under which hundreds of people were killed or forcibly disappeared. But his instructions that the military should mark the coup’s 55th anniversary this Sunday has prompted widespread fury.

“Brazil celebrating the anniversary of the ‘64 coup is like Germany instituting Hitler Day,” tweeted journalist Hildegard Angel, whose brother Stuart was tortured and killed in custody, and whose mother Zuzu died in a traffic accident staged by military agents.

“This makes me enormously sad,” Angel told the Guardian. “It makes me want to leave Brazil.” She noted that the coup actually took place in the early hours of April 1 – known as ‘Liar’s Day’ in Brazil – and said Bolsonaro’s supporters want to rewrite history. “They want to sell a lie to the children of Brazil,” she said.

James Green, a professor of Brazilian history at Brown University in the US, Bolsonaro’s position on the dictatorship made him “the equivalent of a Holocaust denier”.

Bolsonaro’s spokesman said on Monday that the president had told the defence ministry to hold “appropriate commemorations” this weekend, although he left it up to military commanders to decide how such events should be staged.

Official commemorations of the military coup disappeared from the army’s calendar of events during the government of leftist president Dilma Rousseff, a former Marxist guerrilla who was imprisoned and tortured during the dictatorship. Her government launched a truth commission which published an exhaustive report of dictatorship abuses in 2014.

Quick Guide Brazil's dictatorship 1964-1985 Show How did it began? Brazil’s leftist president, João Goulart, was toppled in a coup in April 1964. General Humberto Castelo Branco became leader, political parties were banned, and the country was plunged into 21 years of military rule. The repression intensified under Castelo Branco’s hardline successor, Artur da Costa e Silva, who took power in 1967. He was responsible for a notorious decree called AI-5 that gave him wide ranging dictatorial powers and kicked off the so-called “anos de chumbo” (years of lead), a bleak period of tyranny and violence which would last until 1974. What happened during the dictatorship? Supporters of Brazil’s 1964-1985 military regime - including Jair Bolsonaro - credit it with bringing security and stability to the South American country and masterminding a decade-long economic “miracle”. It also pushed ahead with several pharaonic infrastructure projects including the still unfinished Trans-Amazonian highway and the eight-mile bridge across Rio’s Guanabara bay. But the regime, while less notoriously violent than those in Argentina and Chile, was also responsible for murdering or killing hundreds of its opponents and imprisoning thousands more. Among those jailed and tortured were Brazil’s first female president, Dilma Rousseff, then a leftwing rebel. It was also a period of severe censorship. Some of Brazil’s best-loved musicians - including Gilberto Gil, Chico Buarque and Caetano Veloso - went into exile in Europe, writing songs about their enforced departures. How did it end? Political exiles began returning to Brazil in 1979 after an amnesty law was passed that began to pave the way for the return of democracy. But the pro-democracy “Diretas Já” (Direct elections now!) movement only hit its stride in 1984 with a series of vast and historic street rallies in cities such as Rio de Janeiro, São Paulo and Belo Horizonte. Civilian rule returned the following year and a new constitution was introduced in 1988. The following year Brazil held its first direct presidential election in nearly three decades.

But Bolsonaro’s order coincides with a growing campaign to present the coup as a “democratic revolution” that saved Brazil from communism – rather than the start of a far-right regime that suspended elections, censored the media, executed hundreds of opponents and tortured thousands more.

“The president does not consider 31 March 1964 a military coup,” said the spokesman, General Otávio Rêgo Barros. “He believes that – considering the danger [Brazil] was in – society brought together civilians and the military to put the country back on track.”

The decision was cheered by Bolsonaro supporters. “The real narrative of our history is back,” tweeted Joice Hasselmann, a congresswoman for Bolsonaro’s PSL party.

As the row deepened on Tuesday, the office of the prosecutor general issued a forceful criticism of Bolsonaro’s move.

“If the unconstitutional, violent and anti-democratic defeat of a government wasn’t enough, the coup of 1964 gave rise to a regime that restricted fundamental rights and violently and systematically repressed political dissidence,” it said.

Bolsonaro has gained notoriety for his support for the military regime. While still a congressman, he said: “The dictatorship’s mistake was to torture and not kill more.”

Unlike other Argentina and Chile, which also endured military rule, Brazil never prosecuted dictatorship officials, because of an amnesty law introduced before the return to democracy.

Brazilians on the right argue that the coup was necessary to save the country from communism at a time was Latin America was a cold war battleground.

The trailer for a new documentary on the coup produced by rightwing website Brasil Paralelo has been watched nearly 800,000 times. The film, and a related book, play down the regime’s repression and argue that at the time Brazil was under threat of a leftwing takeover.

Green – whose university has an online archive of 29,000 documents about the military regime including US support for it – rubbished these claims.

“The military used the cold war rhetoric of anti-communism as an excuse,” he said. “They eliminated democracy for 21 years.”

Rio de Janeiro’s Military Club said it would mark this weekend’s anniversary with its usual commemorative lunch. “We have always marked the revolution on 31 March,” said its former president, retired General Gilberto Pimentel. “There is nothing new.”