Amnesty International has accused El Salvador’s government of committing “massive human rights violations” during an extraordinary security crackdown that has seen more than 36,000 people arrested in just over two months.

The clampdown was orchestrated by the Central American country’s authoritarian-minded president, Nayib Bukele, in late March after a sudden eruption of bloodshed that saw 87 murders in a single weekend.

Bukele’s response to those killings was swift and severe, with pro-government lawmakers approving a draconian state of exception which entered its third month last week. This week, Bukele’s security minister, Gustavo Villatoro, claimed 36,277 people had been detained since their “war on gangs” began: 31,163 men and 5,114 women.

If true, that would mean more people have been arrested in El Salvador in the last two months than in the whole of last year. The population of the country’s already overcrowded prisons would have almost doubled since March while almost 2% of the country’s entire adult population would now find itself behind bars.

“What we are doing is responding … to the demands of millions of Salvadorians who are sick of living under the control of these terrorist groups,” Villatoro told state television on Wednesday as Bukele celebrated his third year in power.

“[Critics] haven’t grasped the transformations President Nayib Bukele is bringing to this country,” Villatoro added. He claimed the 40-year-old populist had shown “great courage” in challenging the notorious gangs that were spawned in the US during the 1980s and seized control of much of El Salvador after a bloody 12-year civil war ended in 1992.

Independent polls suggest many of El Salvador’s 6 million citizens agree, with Bukele’s already sky-high approval ratings rising since the state of emergency was imposed.

Yet campaigners, critics and members of the international community have profound misgivings about the stunning wave of arrests, the suspension of basic civil liberties and due process, and the detention of hundreds, possibly thousands of innocent citizens from mostly impoverished communities.

At least 21 prisoners have died while in custody, according to one local newspaper, El Diario de Hoy, with many of those victims reportedly suffering signs of violence or torture. Some of those arrested are reportedly as young as 12.

Erika Guevara Rosa, Amnesty International’s director for the Americas, said brutal and ineffective hardline crime policies had been imposed on many parts of Latin America over the years, from El Salvador and Mexico to Brazil and Colombia, with “perverse” results.

“But we had certainly never seen arbitrary detentions on such a massive scale in such a short space of time,” added the activist who is in El Salvador’s capital, San Salvador, to denounce what she called an “extremely distressing” crisis.

“It’s just devastating to hear families – people who already live in poverty and lack access to healthcare, education and drinking water – now having to worry, not only about where and how their family members are, but also if they will be the next people to be arrested,” added Guevara Rosa.

Propaganda billboards dotting El Salvador’s streets and motorways urge passersby to snitch on suspected criminals by calling an anonymous hotline. “We need your help to continue capturing terrorists,” they read.

“It’s just insane. It is unbelievable,” said Fabricio Altamirano, the owner of El Diario de Hoy, who believed the government’s attempt to turn citizens into informants meant “anybody is in danger” from malicious tip-offs.

“If you have pissed anybody off, you are liable to be thrown in jail … You don’t get a lawyer, you don’t get a phone call, you don’t get rights – and you are thrown in hell,” Altamirano said.

Guevara Rosa called the crackdown the latest step in the “systematic dismantling” of El Salvador’s institutions and “the total collapse of the rule of law” that has played out since Bukele took power on 1 June 2019.

Since then, the social media-obsessed millennial populist – who has sarcastically nicknamed himself “the world’s coolest dictator” and boasts nearly 4 million Twitter followers – has caused international alarm with his breakneck accumulation of power. In one of the most hair-raising incidents, heavily armed troops occupied El Salvador’s parliament in February 2020, in an attempt to bully rivals into supporting Bukele’s security drive.

Last March the president’s party, Nuevas Ideas (New Ideas), won a supermajority in the assembly, giving him vast powers to push through highly controversial initiatives such as this year’s state of exception.

An overwhelming majority of voters celebrate the dramatic drop in violence achieved under Bukele’s presidency, even if independent media reports suggest it was achieved through a secret pact with the gangs that appears to have temporarily collapsed in late March for reasons that remain murky.

“He is buttressed by tremendous popular support … [People] see him as an absolute hero … He couldn’t be more applauded by the majority of the population … It makes wonderful propaganda,” said Altamirano, the newspaper owner, before adding: “It’s all fine and dandy – unless you have a child or son that gets thrown into jail.”