3Any person found committing an offence for which he is liable to be tried by virtue of the said section one hundred and eighteen, or alleged to have committed or reasonably suspected of having committed such an offence, may be arrested by a provost officer, by any officer or person legally exercising authority under a provost officer or on his behalf, or by or on the orders of any officer subject to this Act; and subsection (3) of section forty-five of this Act shall apply to the powers of arrest conferred by this paragraph as it applies to the powers conferred by that section.