Prosecutor Juan Bautista Mendoza said that a further sentence reduction is possible if the women testify against co-conspirators.
Otherwise, they face between eight and 15 years.
Michaella McCollum, of Northern Ireland and Melissa Reid, of Lenzie, both 20, have a court hearing on Tuesday.
McCollum attorney Peter Madden said he could not yet say whether she would plead guilty or go to trial.
After her arrest he said the two women were coerced by a gang of up to 15 armed men.