27.—(1) A person remanded in custody under this Act may be detained in a prison (or, if he or she is not more than 21 years of age, in a remand institution) or, for a period not exceeding 48 hours, in a Garda Síochána station.

(2) A person shall not be remanded on bail or otherwise released from custody under this Act if—

(a)  (i) the person has been sentenced to a term of imprisonment for an offence of which he or she was convicted in the State,

(ii) on the date of his or her being remanded or on which he or she would, but for this paragraph, be entitled to be released, all or part of the term of imprisonment remains unexpired, and

(iii) the person is required to serve all or part of the remainder of that term of imprisonment,

or

(b)  (i) the person has been charged with or convicted of an offence in the State, and

(ii) on the date of his or her being remanded or on which he or she would, but for this paragraph, be entitled to be released, he or she is required to be in custody by virtue of having been remanded in custody pending trial for that offence or the imposition of sentence in respect of that offence.