MICHAELLA McCollum Connolly and Melissa Reid face a minimum of six years and eight months in prison with no eligibility for parole, even if they plead guilty, a prosecutor has said.
But prosecutor Juan Bautista Mendoza said a further sentence reduction was possible if the women cooperated as witnesses against co-conspirators.
Michaella, from Dungannon, and her Scottish co-accused are behind bars in Peru, having being caught last month trying to board a flight to Spain with cocaine in their luggage.
The young women, both 20, have a Tuesday court hearing where they are expected to be interrogated by a judge.
Each faces drug-trafficking charges and could be charged with up to 15 years in prison. Mr Mendoza said that if both women plead guilty they could be sentenced to prison in less than a month's time. He said otherwise their trial could last six months.
The prosecutor said a new law eliminated sentence reductions for good behaviour for people convicted of drug trafficking.
The pair have insisted that they were kidnapped at gunpoint in Spain, and then forced to travel to South America in order to smuggle the drugs.
Attorney Peter Madden said yesterday he could not say whether Michaella would plead guilty or go to trial.