The Special Jurisdiction for Peace tribunal, known by its Spanish acronym JEP, came into being under Colombia's historic 2016 peace agreement with the Marxist rebel army FARC.

It is tasked with investigating the worst crimes committed during FARC's half-century-long insurgency.

In 2021, the tribunal said 6,402 cases of "false positives" -- recording murdered civilians as fallen guerrillas to inflate military successes -- had occurred between 2002 and 2008.

But on Tuesday, it said the real figure was more than 20 percent higher, after widening the period under investigation -- from 2002-2008 to 1990-2016 -- and receiving information from new sources.

"It is most likely that even this new figure will increase in the future," JEP President Alejandro Ramelli said during a hearing.

In an X post, Colombia's left-wing President Gustavo Petro called the phenomenon "the worst crime against humanity committed in the Americas this century."

Most "false positive" cases occurred during the 2002-2010 presidency of Alvaro Uribe, known for his iron-fisted crackdown on insurgents.

Several military personnel, including high-ranking officers, have confessed before the JEP to killing young men and passing them off as insurgents, sometimes under pressure from superiors.

Some of those murdered were changed into guerrilla uniforms and their bodies presented to the press in what became the worst scandal in the history of Colombia's military.

The JEP offers alternatives to jail time to people who confess their crimes and make reparations to victims.

Last year, it sentenced a group of former soldiers to eight years of reparations over the murders of 135 civilians.

It also ordered seven FARC leaders to engage in eight years of activities to promote healing over more than 21,000 kidnappings carried out by the group.