Soldiers from the Atlacatl Battalion executed 986 people, including 558 children, in northeastern El Mozote and neighboring communities between December 9 and 13, 1981.

The victims were accused of collaborating with the leftist Farabundo Marti National Liberation Front (FMLN).

Rights group Cristosal reported 13 of the alleged perpetrators will face trial, citing a resolution issued November 26 by the Investigative Court of the city of San Francisco Gotera.

Former defense minister Jose Guillermo Garcia and 12 other officers will be tried for charges of murder and rape unless they are able to successfully appeal the trial, according to Cristosal.

The recent progress in the El Mozote case "has been made possible thanks to the crucial testimonial evidence courageously provided by the survivors of the massacre and forensic investigations," Cristosal said.

A separate group representing the families of the massacre victims hailed the decision as a "victory" after more than two decades of struggle.

"It's like finding a glimmer of light... in the middle of so much adversity," Leonel Tobar, the group's president, told AFP.

He expressed confidence that the judge could issue a ruling no later than next year, given that the case had been "clearly proven."

No date has been set in the latest trial, but 92-year-old Garcia and two other former military leaders have already been sentenced to prison for the murder of four Dutch journalists in March 1982.

In that case, the three defendants were sentenced to 60 years but will serve the 30-year maximum legally allowed.

In July, Cristosal suspended operations in El Salvador, citing escalating repression of humanitarian activists under Salvadoran President Nayib Bukele, and continued operations from Guatemala.

The massacre -- the worst in recent Latin American history -- took place during the Salvadoran civil war, which ran from 1980 to 1992.

The war left 75,000 people dead and over 7,000 missing, and devastated the country's economy.