The Egyptian trial of Irish man Ibrahim Halawa has been postponed for the 18th time.

Mr Halawa, who last month celebrated his 21st birthday, has spent almost three and a half years in prison.

Amnesty International has declared him a Prisoner of Conscience. He was 17 when he was first detained in August 2013.

It says based on a thorough review of his case, the organisation determined that he could not have committed the serious crimes which he was accused of.

"He has been imprisoned solely for peacefully exercising his right to freedom of expression and freedom of assembly", the group claims.

Speaking after the postponement, Foreign Affairs Minister Charlie Flanagan said: "My thoughts are with Ibrahim Halawa and his family today. I note that there has been yet another adjournment in the case to February 14th.

"However, there appears to have been some progress in the trial at today's hearing, with a number of witnesses called and questioned.

"I sincerely hope that this indicates that the trial is finally now moving forward and that there will be an early conclusion."

Ireland's ambassador to Egypt, Damien Cole, and a team from the embassy was in court for the hearing.

The Irish embassy will also be represented at the next hearing.

"The Irish Government is continuing to give its full support to efforts to secure Ibrahim Halawa’s freedom and his return to Ireland as soon as possible, and we will be maintaining our engagement with the Egyptian authorities to that end", Mr Flanagan said.

Minister Flanagan says he also spoke with the Egyptian Foreign Minister, Sameh Shoukry, about the case on Monday.

"We are all united in our determination to see this young man - who has spent almost three and a half years in prison without having been convicted of any wrongdoing - back home with his family and friends in Ireland at the earliest possible time", he added.

"Horrendous conditions"

Colm O’Gorman, executive director of Amnesty International Ireland, said: "This young Irish citizen has now been detained for almost three and a half years. In this time, he has experienced unfathomable suffering.

"He has endured eighteen delays in his mass trial and spent 41 long months living in horrendous conditions in an Egyptian prison cell.

"Ibrahim’s ongoing detention is a clear and inexcusable violation of both Egyptian and international human rights law.

"Amnesty International remains gravely concerned for his physical and mental well-being.

"It is long past time that the Egyptian authorities respect international human rights law and allow this young Irish citizen to return home."

His trial has been rescheduled for February 14th.

Last week, reports emerged that Egyptian President el-Sisi said he will be released and returned to Ireland upon completion of his trial.

"Though this development might appear encouraging, Ibrahim’s release is dependent on the completion of an unfair judicial process. Today, following the eighteenth postponement, there is no sign that this unfair mass trial will conclude soon," Mr O'Gorman added.

A cross-party delegation from the Oireachras met Mr Halawa during a recent visit to Egypt.