Human Rights Watch (HRW) accused Salvadoran authorities on Friday of "mass due process violations" in the detention of tens of thousands of people, including hundreds of children, in over-crowded prisons, citing leaked government data.
The rights watchdog said following the introduction of a state of emergency suspending key rights to address gang violence in March last year, tens of thousands had been put into overcrowded prisons for "broadly defined crimes".
The state of emergency remains in force after multiple extensions, despite criticism from human rights groups.
El Salvador's government did not immediately respond to a late night request for comment from Reuters.
"This leaked database points to serious human rights violations committed during the state of emergency," said Tamara Taraciuk Broner, acting Americas director at HRW, which said more than 61,000 people had been arrested since March.
Reuters was not able to independently confirm the data.
HRW said the database was from the country's public safety ministry and listed people prosecuted between March and August last year. It showed that close to 1,082 children, largely boys, had been sent to pre-trial detention as of August, HRW said.
This was made possible under a March 2022 law that lowered the age of criminal responsibility in gang-related crimes from 16 to as young as 12, it added.
Citing the database, the HRW added that dozens have died in custody, mostly at the country's Izalco and La Esperanza prisons which respectively held three and four times as many prisoners they were designed to house.
Other prisons, such as Ilopango's women's prison and San Miguel, for men, were six times over capacity, it said.
More than 50,000 people were sent to pre-trial detention as of late August, the group said, while nearly 40,000 were charged with "unlawful association", a crime which includes people who take part in gangs or receive "indirect benefits".
Authorities also charged 8,000 with membership of a "terrorist organisation", a broad term under Salvadoran law which the Human Rights Watch said opens the door for arbitrary arrests and does little to ensure justice.