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.
The guilty pleas made by Melissa Reid and Michaella McCollum, arrested with almost 12 kilos of cocaine in their luggage in Peru, will not be accepted, the prosecution said.
Yesterday the pair pleaded guilty to drug trafficking charges in front of a judge. However anti-narcotics prosecutor Juan Rosas said that as the new plea only claimed partial guilty for their actions, it would not be accepted by the prosecution.
Mr Rosas said the women would have to release a new statement, admitting they made up the story about being kidnapped and threatened. He said:
"A new statement is required by the women and they will have to admit not only that they came here to traffic drugs but also that they did not tell the truth with respect to them being kidnapped.
"They have to make a full admission of responsibility for all of the charges brought by the prosecution."
The mother of Melissa Reid, the 20-year-old British woman held in Peru along with Michaella McCollum, told ITV's This Morning that she was pleading guilty to get back to her family. Speaking ahead of today's reported guilty plea, she said:
She was definitely carrying the drugs in her luggage. That's for sure.
But we still believe she was coerced into it. Obviously now we realise she needs to plead guilty just to get her home.
The two had the option of pleading guilty in exchange for a lower sentence.