Sch 4A para 4
(1) This paragraph applies if a relevant officer has reasonable grounds to suspect that an offence under section 24B, 25, 25A or 25B of this Act or section 21 of the 2006 Act has been, or is being, committed on the ship. (2) The relevant officer may arrest without warrant anyone whom the ... officer has reasonable grounds for suspecting to be guilty of the offence. (3) The relevant officer may seize and retain anything found on the ship which appears to the officer to be evidence of the offence (but not including anything that the ... officer has reasonable grounds to believe to be an item subject to legal privilege). (4) A power conferred by this paragraph may be exercised on the ship or elsewhere.