The European Parliament has agreed to table an urgent motion for resolution next week calling for the release of Ibrahim Halawa.
The plight of the Irish teenager, who faces the death penalty in Egypt, is to be raised in Strasbourg on Thursday.
Sean Kelly, MEP for Ireland South, has given his "full support" to the teenager, incarcerated in Egypt since 2013.
The resolution, authored by Mr Kelly, is expected to be debated by the entire European Parliament before a vote on the text on Thursday.
Its adoption would likely be viewed as a strong message of support for Mr Halawa from the EU.
Thousands of well-wishers have sent messages to Mr Halawa as he prepares to spend a third birthday behind bars. His 20th birthday is on Sunday, December 13th.
Mr Halawa is said to have endured “torture and inhumane treatment” - including regular beatings - while in detention at the notorious Wadi Natrun prison, where guards are alleged to have used electricity and even “crucifixion” on inmates.
The Dubliner was aged 17 when in August 2013 he was arrested by the Egyptian army as he took refuge in a Cairo mosque while Muslim Brotherhood protesters staged a "day of rage" outside.
Ousted from power
Demonstrators had taken to the streets after their elected leader, Mohamed Morsi, was ousted from power in a military "coup", leading to a crackdown ordered by army chief Abdel Fattah al-Sisi, now the country's president.
It is feared Mr Halawa, who was on his summer holiday in the Egyptian capital when violence flared, could face the death penalty when a mass trial of 494 alleged dissenters resumes on Tuesday. The legal proceedings have been repeatedly delayed since 2013.
The campaign group claims the teenager has described “experimental torture techniques” to his family in messages sent from jail.
A birthday card organised by human rights group Reprieve and signed by more than 8,000 people was presented to the Egyptian embassy in London, although officials refused to accept it when it was delivered by hand on Friday night.
Maya Foa, director of Reprieve's death penalty team, said: "It is a total disgrace that Ibrahim Halawa is spending a third birthday behind bars in Egypt, awaiting a mass trial that makes a mockery of justice.
“It is plain to see that the Egyptian courts offer no hope of justice - just the real threat of a death sentence handed down en masse.
"The Irish Government and other countries that are closely allied with Egypt - including the UK - must urgently push for Ibrahim's release, before it's too late."
According to Reprieve the Egyptian government has sentenced nearly 600 people to death in the year, with most alleged crimes linked to political protest.
Early last month Halawa’s legal team, made up of lawyers from Ireland and Britain, had written to British prime minister David Cameron to raise his case with the Egyptian president during his visit to London.
They set out the “long list” of violations of the youngster’s rights and the incompatibility of any mass trial with “the most basic judicial standards of fairness”.
Mr Halawa’s Belfast-based solicitor Darragh Mackin said they had received no indication of whether Mr Cameron did in fact raise his client’s situation with the Egyptian leader.
Should the trial go ahead the hundreds of defendants would be tried under similar rules to the “joint enterprise” system in the UK, except on a vast scale.
“Individuals are not going to get the chance to represent their case. They are effectively charged under joint enterprise,” he said.
Mr Hawala’s mother is understood to have flown to the country to visit him in jail, although her only contact with her son would be through a narrow gap between two cages, Mr Mackin said.