Former Defences Forces member Lisa Smith has had her period of detention extended for a further 24 hours.
Her period of detention was extended by a judge at a special sitting of Dublin District Court.
Ms Smith was in court for the hearing and has now been returned to Kevin Street Garda Station, where she can be detained until 10.30am tomorrow, by which time she must either be charged or released.
The 38-year-old, who was deported along with her young daughter from Turkey on Sunday, is the subject of a criminal investigation into suspected commission of terrorist offences abroad.
The Co Louth woman travelled to Syria in 2015 to join the Islamic State group after converting to Islam several years before.
The legal firm representing her has already said she is co-operating with gardaí and categorically denies any involvement in any terrorist organisation or activities.
Detectives are interviewing her under caution about her activities, movements, communications and contacts online and in person in Africa, Europe, the Middle East and Ireland since she converted to Islam.
Her daughter is being cared for by relatives.
The special court sitting lasted around an hour and after hearing evidence as to why gardaí needed more time to question Ms Smith, Judge Patricia McNamara granted the detention extension.
Ms Smith was represented by solicitor Peter Corrigan at the hearing and the judge stressed that strict reporting restrictions were in place in relation to the garda application.