The guilty pleas made by Michaella McCollum and Melissa Reid have not been accepted because the British women need to provide more information on who supplied the drugs they were found with at Lima airport, prosecutors said.
The two drug mules' guilty pleas have not been fully accepted, as far as the prosecutor is concerned, until they give more details.
They will be asked to give another statement before the judge explaining where the drugs came from, who supplied them and why they said they had been forced to carry them by an armed gang.
More top news
Thousands of pounds worth of heroin has been found stashed inside the covers of children's books at Heathrow Airport.
Internet search engine says Cilla Black was the subject of more online searches than Kim Kardashian this year, beaten only by Taylor Swift.
A supermarket price war and fierce competition across the rest of the high street has seen shop prices slumped by a record level last month.