ISTANBUL: At least five to six 'unauthorized armed persons' boarded a merchant vessel off the coast of Somalia, the United Kingdom Maritime Trade Operations (UKMTO) said on Thursday. 'Crew mustered in citadel,' UKMTO said in a brief statement, referring to the room on a vessel dedicated for those on board to shelter in case of an attack. It warned that the ship's navigational lighting is 'limited and is likely to be below minimum anti-collision regulation specification.' UKMTO advised vessels to transit with caution and report any suspicious activity. Source: Anadolu Agency