Photograph: Anadolu Agency/Getty Images
Photograph: Anadolu Agency/Getty Images© Provided by The Guardian

The human cost of El Salvador’s controversial “war on gangs” has been laid bare in a new report which claims dozens of prisoners were tortured and killed in jail after being caught up in the year-long security crackdown.

The detailed 107-page report from human rights group Cristosal said at least 153 people had died in custody after being arrested as part of President Nayib Bukele’s year long offensive against the Central American country’s notorious “pandillas”.

Related: El Salvador crackdown breaks the gangs – at huge cost to human rights

The NGO said it had confirmed 29 of those fatalities as violent deaths and another 46 were considered. In most of those 75 cases, Cristosal said the bodies of the victims showed signs of torture, beatings or strangulation. Other dead inmates also showed signs of injuries but were classified as having died of “undetermined” or “natural” causes meaning the true number of violent deaths could be higher.

The rights group said it had obtained photographs and mortuary reports showing bodies with signs of “asphyxiation, [bone] fractures, significant bruising, lacerations and even perforations”. Some appeared to have died of malnutrition. Nearly half of the victims were men aged between 18 and 38. The NGO claimed some prisoners had been tortured with electric shocks.

Cristosal’s director, Noah Bullock, said its findings highlighted how human rights violations were “a systematic practice rather than an exception” under El Salvador’s current government.

The human rights group based its report on interviews with dozens of relatives of the deceased and former inmates, as well as official forensic reports and field work.

El Salvador’s government has rejected criticism of its anti-gang campaign, which has seen more than 67,000 people arrested since its began in March 2022. It dismisses critical NGOs and media organizations as defenders of gangs and “terrorists”.

North American crypto enthusiasts have championed El Salvador’s Bitcoin-loving authoritarian leader and his gang clampdown, as have right-wing populists in other Latin American countries struggling with violent crime.

Even government critics admit the crackdown – which looks set to guarantee Bukele a second term in next year’s presidential election – has brought dramatic change to poor Salvadoran communities which for years lived under the brutal rule of gangs.

“The dismantling of gangs has enormous life-changing potential for the country,” the trailblazing news outlet El Faro reported earlier this year after chronicling the groups’ apparent dissolution in a 5,000-word investigation. “They have ruined the gangs as you knew them,” one senior gang boss told El Faro.

However, those advances have come at a high cost for El Salvador’s democracy, human rights, civil liberties and the thousands of broken families whose members have been caught up in the government offensive.

Related: ‘They found hell’: innocent foreigners caught in El Salvador’s mass arrests

Vilma Mancía said she had been forced to raise her six grandchildren after both her two children, aged 22 and 29, were both jailed during the crackdown. “Nobody helps me, not even to find food … I don’t know what to do,” said the 65-year-old from Apopa who was recently diagnosed with stomach cancer.

Last year the Guardian documented the case of one young Salvadoran who died in mysterious circumstances shortly after being arrested in Salcoatitán, a tourist town in El Salvador’s coffee-growing heartlands.

Juan José Ibáñez García – a 21-year-old restaurant worker who friends claimed had no links to crime – died last May, a fortnight after being arrested.

“We had so many dreams … to be parents; to build a business together; to study together … and it’s all gone,” said his 23-year-old girlfriend, Sandra García, who admitted she had helped elected Bukele in 2019.

“So many Salvadorans put our trust in [Bukele] – and we were cheated,” García added.