Four men have been detained under the Immigration Act after police boarded a cargo ship amid reports of stowaways threatening crew.
Essex Police said the vessel was boarded at around 11pm on Friday and was taken to the Port of Tilbury in Essex.
It arrived on Saturday morning and no one was injured, officers said.
The men, who had locked themselves on the bridge of the vessel, were found on board and were armed with iron tubes.
Grimaldi Lines, the ship’s operator, has said the four stowaways wanted the ship to navigate close to the coast.
Essex Police earlier said the incident was not being treated as a “hostage, piracy or terror related incident” but that it was a “complex incident”.
The vessel is the Grande Tema, a 71,000-tonne ship which set off from Lagos, Nigeria, on December 10, and is currently sailing round in circles in the estuary.
Paul Kyprianou, a spokesman for Grimaldi Lines, the operator of the ship, told Sky News: “We found four stowaways on the vessel.
“The vessel was coming from Nigeria and was bound to Tilbury and those four stowaways were in the cabin, and today they managed to escape from the cabin and they started threatening the crew, requesting the master of the vessel navigating very close to the coast.
“That request was probably because they wanted to jump and reach the British coast.
“The crew reacted and they locked themselves in the bridge of the vessel and so they are safe, we haven’t had any injuries.”
He added: “The master is in continuous contact with the UK authorities, particularly with the Essex Police and the coastguard. We are waiting to see what is going to happen, we expect authorities to intervene.”
Kyprianou continued: “They managed to get some, whatever they could find on the vessel, pieces of iron tubes and things like that that they were using in order to threaten.
“It’s a small group but obviously you can understand it would be scary.
“The problem is the four people free on the deck threatening members and requesting them to get closer. No injuries so far but obviously it’s a tense atmosphere.”