Peter Madden, who is representing Michaella McCollum, 20, from Northern Ireland, said she and Melissa Reid, also 20, from Scotland, are scared and confused but will have to decide within weeks whether to plead guilty or protest their innocence at a trial. Mr Madden said: "They are confident enough that what they have told authorities will be eventually proved.
"The Peruvian system is still that they are innocent until proven guilty but in reality they have to try to prove that what they said happened to them did happen."
Mr Madden, a human rights solicitor who has acted for high-profile republicans, has just returned from South America.
He added: "They are frightened. They are unsure of their future. They are in a prison in which they are the only two foreigners."
Both women are being held in a classification unit at the notorious Virgen de Fatima jail in Lima, which houses some of the country's most dangerous criminals.
The women were stopped with 24lb of cocaine, worth £1.5 million, hidden in their luggage while trying to board a flight to Spain.