The rebel group has been in peace talks with the government since last November, and leaders will be charged over recruiting child soldiers even if a peace accord is reached and some kind of amnesty for other offenses is applied, prosecutor Leonardo Cabana told the newspaper El Espectador.
The figure applies to recruitment since the FARC rose up against the government in 1964. Children as young as eight were assigned tasks of patrolling and "urban support," Cabana was quoted as saying.
The FARC, or Revolutionary Armed Forces of Colombia, recruited minors in 31 of the country's 32 departments, the report says.
Charges will be filed against senior FARC leaders even if a peace accord is reached and those leaders embrace a so-called transitional justice option that suspends jail terms and allows them to get involved in politics, Cabana said.
It was a stated FARC policy to recruit youths of 15 on up but kids as young as eight were also enlisted in the rebel army, Cabana was quoted as saying.