Ibrahim Halawa's application for release on bail has been refused by a court in Cairo.
The 19-year-old from Tallaght in Dublin appeared in court in Cairo today as part of an ongoing mass trial of 494 people.
The trial was adjourned again until the 6 June.
Ibrahim Halawa's mother was in court for today's hearing.
It is understood Ibrahim and the other 493 people involved in his mass trial were detained in a glass box in the courtroom during the hearing.
Ibrahim's family says he could not hear what the judge was saying or what was happening in court from within the box, and that the defendants were shouting to the judge that they could not hear.
Somaia Halawa has told RTÉ News that the court heard from three witnesses today, and it is expected that more witnesses will be called at the next hearing.
Amnesty International has said most of the witnesses due to be called in the trial are police officers or government officials.
Somaia says her family are very concerned about Ibrahim's welfare in prison.
Ibrahim was moved recently to a different section of Wadi-al-Natrun prison, but Somaia says her family are worried about the conditions in which he is being detained and want him to be moved to a different section of the prison.
The family have expressed disappointment at the way the Government has responded to the case, and have asked for the Taoiseach to intervene directly.
Minister for Foreign Affairs Charlie Flanaga has expressed his disappointment that the bail application, which he says the Government had supported, has been refused along with all other bail applications in the case.
Minister Flanagan said the Government's objectives in the case remained clear - to see Ibrahim Halawa released by the Egyptian authorities, and to provide consular support while he remains in detention.
He said that with the Taoiseach's full support, he remained committed to taking all appropriate action in pursuit of these objectives towards achieving a positive outcome for Ibrahim and his family.
The minister is due to meet the Egyptian Foreign Minister Sameh Shoukry in New York tomorrow.