Northern Irish woman Michaella McCollum Connolly, 20, and Scot Melissa Reid, 19, were due to appear before a court in Lima on Wednesday to hear the charges against them.
But the hearing was delayed, reportedly due to difficulties finding an interpreter to help their Peruvian lawyer.
Michael Russell, the former honorary consul of Ireland in Peru who visited the women on Tuesday, believes proceedings will begin on either Friday or Monday.
“It has to be by next Wednesday anyway by law,” he told Morning Ireland.
“They will be taken to the court… where they will be formally charged and assigned to prison.”
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