A 35-year-old Nigerian doctor, who has been detained in Mountjoy jail for six days, is expected to go to the High Court today to challenge his imprisonment.
Dr Grant Oyeye was arrested as he arrived at Dublin Airport last Tuesday.
He had enrolled in a two-month course in tropical medicine at the Royal College of Surgeons.
Solicitors for Dr Oyeye said he was detained despite having a passport, an entry visa and a substantial sum of money.
He was held pending deportation after immigration gardai were informed that the hospital where he reported he was an employee had not seen him for six months.
However, Dr Oyeye's lawyers said it has since been established that during that period, he had been attached to an ancillary hospital.
It is understood that he spent the first three nights of detention in the basement of Mountjoy before being transferred to the jail's training unit.