The former Justice Minister says the Egyptian ambassador to Ireland, Soha Gendi, should be expelled if Ibrahim Halawa isn't released by the end of the week.
The 21-year-old Dubliner was acquitted three weeks ago after a mass trial, but has yet to be freed from an Egyptian prison.
Foreign Affairs Minister Simon Coveney says bureaucracy is holding up his release and that their pleas to have it fast-tracked have fallen on deaf ears.
But former Justice Minister Alan Shatter says the Government needs to go further.
"We were in difficulty as long as there was a pending trial. It was unacceptable it took so long for the trial to take place," he said.
"But now we know there is an innocent Irish citizen, incarcerated in a jail in Egypt found innocent by the Egyptian courts.
"I believe the Egyptian ambassador should be brought in and she should be told if he isn't released, she should be expelled."