Seven Nigerian men seized after British special services stormed an oil tanker off the Isle of Wight have been bailed, police said.
But they will still be detained by the Border Force as an investigation into the incident continues.
The raid was carried out by around 16 members of the Special Boat Service (SBS), backed by airborne snipers, who secured the Nave Andromeda tanker in around nine minutes.
It came amid reports stowaways had boarded the vessel and attempted to hijack it.
The operation was authorised by Defence Secretary Ben Wallace and Home Secretary Priti Patel on Sunday night after a tense 10-hour stand-off.
“The seven arrested men, who are all Nigerian nationals, have subsequently been bailed in relation to the criminal investigation whilst investigators continue their inquiries, but will now remain detained under Border Force powers.”
Hampshire Police previously said the force was alerted to concerns over the welfare of the crew of the 748ft (228m) Nave Andromeda soon after 10am on Sunday as the ship headed towards Southampton, having set sail from Lagos in Nigeria.
The ship’s operator, Navios Tanker Management, said the stowaways “illegally boarded” the Liberian-flagged tanker in Lagos.
All other members of the crew went to a secure area on the vessel for their own safety, except for the engineer – another Greek national – who remained in the engine room taking instructions from the master.
The SBS is the elite maritime counter-terrorism unit of the Royal Navy, with most of its personnel Royal Marine Commandos, whose operations are highly classified and not officially confirmed.
On Sunday, four military helicopters – thought to have included two Merlin Mk4s, a Wildcat and a Chinook – took 40 personnel to the scene of the suspected hijack aboard the Nave Andromeda and about 16 members of the SBS boarded the vessel.
Before the armed forces action, Hampshire Police said the vessel had been located around six miles off the coast of Bembridge on the Isle of Wight, adding: “It was reported that a number of stowaways were on board and they had made verbal threats towards the crew. No-one has been reported injured.”
An exclusion zone with a three-mile radius was placed around the vessel, with two Coastguard helicopters spotted circling the ship in the afternoon.