It is believed the teenager and a friend, both 17 and from Cameroon, stowed away on the Thueland without food for two weeks.
He said: “They were quite well hidden but also quite exposed. “They stowed away there apparently with no food or water for two weeks while the vessel came up from Cameroon. “It must have been horrendous. They must have been very, very desperate.” Coastguard search
Coastguards said the French-speaking teenagers had been found hiding in the ship’s rudder trunk for two weeks with no access to the main ship.
Search teams were called to look for the missing boy on Friday evening after a harbour boat picked up the first teenager who told police his friend had jumped into the water before him and got into difficulties.
A search was launched involving coastguard teams, a helicopter and lifeboats, but the second boy has not yet been found.