Where any person is found carrying or conveying any arms or ammunition whether covered by a licence or not, in such manner or under such circumstances as to afford just grounds of suspicion that the same are or is being carried by him with intent to use them, or that the same may be used, for any unlawful purpose, any magistrate, any police officer or any other public servant or any person employed or working upon a railway, aircraft, vessel, vehicle or any other means of conveyance, may arrest him without warrant and seize from him such arms or ammunition.