The Special Boat Service retook an oil tanker off the Isle of Wight coast in just seven minutes after reports of 'Nigerian stowaways' on board becoming violent and 'threatening the crew'.
Crew members reportedly sought shelter in a safe room on the Liberian-registered oil tanker, named the Nave Andromeda, which was due to arrive at Southampton at 10.30am.
The Special Boat Service landed 16 personnel aboard the vessel via air and sea, with two Royal Navy Merlin helicopters and two Wildcats also used in the operation, Sky News reported.
A frigate, believed to be HMS Richmond, was also on standby but not needed during the operation, which was completed in around seven minutes.
Tobias Ellwood, chair of the House of Commons' Defense Committee, confirmed the action and said no one was hurt. The stowaways are now in custody.
A Ministry of Defence spokesman said: 'In response to a police request, the Defence Secretary and Home Secretary authorised Armed Forces personnel to board a ship in the English Channel to safeguard life and secure a ship that was subject to suspected hijacking.
'Armed forces have gained control of the ship and seven individuals have been detained. Police investigations will now continue. Initial reports confirm the crew are safe and well.'
Reports claimed that the captain of the Nave Andromeda - believed to be capable of carrying 42,000 tons of crude oil with around 15 to 20 crew on board - put out a 'desperate' call for rescue because he 'feared for his life' as stowaways smashed glass on board and even made threats to kill.
It was originally suggested that the tanker had been hijacked, but lawyers representing the owners of the vessel, which had come from Nigeria, today told the BBC the incident was '100 per cent not a hijacking' (pictured: The stern of the oil tanker Nave Andromeda is lit up by police boats as the SBS stormed the tanker this evening)
Seven suspects have been detained aboard an oil tanker off the Isle of Wight following reports that say 'Nigerian stowaways' aboard the vessel were violent towards the crew, reports say
Officers and coastguard crews were called after a group of stowaways were reportedly discovered on a Liberian-registered ship as it made its way to Southampton
The Special Boat Service aircraft used in today's operation
Two Royal Navy Merlin helicopters and two Wildcat helicopters were reportedly used during the operation today, which saw 16 SBS personnel board the Nave Andromeda crude oil tanker via air and sea.
Two Merlin Mk2 helicopters, which supply the UK’s Maritime Force Protection, were mobilised.
A minimum of five crew man the aircraft.
It is armed with Sting-Ray Torpedoes, Mk11 Depth Charges (for targeting submarines) and the M3m .50 Calibre Machine Gun.
The main base for both training and front-line of the aircraft is at RNAS Culdrose in Cornwall.
The Royal Navy has 30 Mk2 helicopters, costing £2.4m.
Wildcat HMA Mk2
Top speed: 157 knots
Two Wildcat helicopters were used during the mission, a multi-role ship-borne helicopter that specifically operates from the frigates and destroyers of the Royal Navy.
The maritime attack helicopter can be flown in extreme conditions all year round.
The Wildcat HMA Mk2 is used in anti-surface warfare, force protection and counter-piracy as well as carrying out an anti-submarine role.
The Wildcat Maritime Attack Helicopter can carry Sting Ray torpedoes, a door-mounted 0.5" heavy machine gun, and light and heavy variants of the Future Anti-Surface Guided Weapon Missiles.
It was originally suggested that the tanker had been hijacked, but lawyers representing the owners of the vessel, which had come from Nigeria, today told the BBC the incident was '100 per cent not a hijacking'.
A source close to the shipping company said that crew had been aware of stowaways on board for some time, but that they had turned violent as the vessel approached Britain. The crew then retreated to the ship's secure citadel, where attackers are unable to enter, the source added.
Stowaways on board Nave Andromeda made 'verbal threats towards crew' but no-one has been reported injured, according to Hampshire police.
The crude oil tanker was currently to the south of Bembridge. Two coastguard helicopters were scrambled to the scene and were spotted circling the ship on Sunday afternoon, while an exclusion zone of five nautical miles was set up in the area south of Sandown.
Home Secretary Priti Patel said: 'Tonight we are thankful for the quick and decisive action of our police and armed forces who were able to bring this situation under control, guaranteeing the safety of all those on board.'
Maritime Risk Expert Christopher Parry told Sky News: 'This sort of thing is the sort of thing the SBS trained to do. Ever since we had oil rigs in the North Sea this sort of operation has been the bread and butter to the Special Boat Service and specialist commandos.
'We want to send out a message - don't mess with us. Don't try and come into our maritime zone and expect to stowaway, or indeed come in for any other reason, you will be met with appropriate force if necessary.'
A source on the Isle of Wight claimed during a mayday call this morning the captain told an operator 'I'm trying to keep them calm but please send help.'
The source said: 'The captain clearly stated he feared for their lives and needed urgent assistance, they needed rescuing... It was desperation, you could hear the fear in his voice.'
A Hampshire police spokesman said: 'At 10.04am today (25 October) concerns were raised to police for the welfare of crew on board the Nave Andromeda - a vessel situated approximately six miles off the coast of Bembridge, Isle of Wight.
'The vessel had been travelling in the direction of Southampton.
'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, is currently in place near the vessel.
'Police are currently working closely with our partners, including the Maritime and Coastguard Agency and Border Force, to bring this incident to a safe conclusion.'
Reports indicated that seven stowaways may have boarded in Nigeria, though this remains unconfirmed.
One coastguard helicopter could be seen circling the tanker, as viewed on Plane Finder, while the 748-foot vessel has made a number of zig-zags in the area, according to Marine Traffic.
A Hampshire police spokesman had earlier said: 'We are aware and dealing with an ongoing incident on board a vessel which is situated south of the Isle of Wight.
'We will provide you with further updates when we are in a position to do so.'
A spokeswoman for Associated British Ports (ABP), which runs Southampton port, said they had not had any contact with the vessel and they had no further comment.
The Nave Andromeda is a crude oil tanker which carries the Liberian flag. The tanker was seen taking a ziz-zag type path near to the Isle of Wight today
The vessel was due to be heading to Southampton this morning (pictured left). A more zoomed in version (right) shows how the ship made a number of zig-zag movements
A coastguard helicopter was circling the Nave Andromeda near to the Isle of Wight following reports of an incident
Crew members had reportedly been sheltering on the ship, named the Nave Andromeda - a crude oil tanker which is currently south of Bembridge, according to Isle of Wight Radio
The Coastguard said: 'We are currently assisting Hampshire Constabulary with an incident on board a vessel situated off the Isle of Wight.
'The search and rescue helicopters from Lee on Solent and Lydd are in attendance.'
The incident will likely lead to involvement from the Royal Navy and the Special Boat Service.
The Nave Andromeda was built in 2011 and weighs 42,338 tonnes. It was last known to be docked in Lagos, Nigeria on October 6. Though the ship is registered in Liberia, it is understood the ship is Greek-owned.
Speaking about the incident to Sky News today, Conservative MP for the Isle of Wight, Bob Seely, said marine counter-terrorism forces will likely be called in, while a COBR meeting is likely to be held, or has been already.
He said: 'Despite being told not to drop anchor, the skipper has dropped anchor and the ship may be now under the control of stowaways on the ship.
'They will be looking at the ship's registration, who's on it, what it is carrying, how many stowaways there are, can they get in contact with the crew if they can't get in contact with the skipper.'
He said authorities are also likely to be planning how to get onto the ship.
Meanwhile, Southampton Itchen MP Royston Smith said the incident was 'shocking'.
A police officer observes Nave Andromeda, which is anchored off the east coast of the island following reports of the vessel being seized by hijackers earleir today
A restriction zone of five nautical miles is now in place around the vessel, while a coastguard helicopter is also circling the ship, according to Sky News
A Police officer on the Isle of Wight keeps watch on a crude oil tanker called the Nave Andromeda off Isle of Wight coast after a 'security incident' was reported
The Nave Andromeda was built in 2011 and weighs 42,338 tonnes. It was last known to be docked in Lagos, Nigeria on October 6. Though the ship is registered in Liberia, it is understood the ship is Greek-owned (pictured: The ship off the Isle of Wight coast)
The Conservative MP told the Daily Echo: 'I know our emergency services will be handling this in the professional way they always do and my thoughts are with those crew members who are on the ship.
'I hope this situation is brought to a safe and successful conclusion as quickly as possible.'
Mick Cash, general secretary of the maritime union RMT, urged the government to do 'all it can to prevent harm coming to crew or anyone else'.
He said: 'This is a troubling incident which must not escalate to further jeopardise crew welfare or maritime safety in what is an extremely busy area for merchant shipping.
'We must call on all parties, including the Greek shipowner to take action to resolve this incident safely and quickly.'
A UK Chamber of Shipping spokesperson said: 'We are aware of an incident onboard the Nave Andromeda off the Isle of Wight and are in contact with the relevant authorities.
'We believe it is likely to be related to stowaways onboard but are awaiting more information.'
The incident comes after an incident in which a group of stowaway ran amok on a cargo ship in the Thames Estuary in December 2018.
The men, from Nigeria and Liberia, waved metal poles and threw faeces and urine after being found hiding on the vessel, which was bound for Tilbury docks in Essex.
The group demanded to be dropped off in Britain. They were arrested and jailed in January for affray offences following a trial at the Old Bailey in January.
Today's incident is near to the location where the 52,000 ton cargo ship the Hoegh Osaka was deliberately grounded to prevent it from capsizing after it began listing as it left port.
The vessel, which was carrying 1,400 cars, including Rolls Royces and Bentleys, became grounded on Bramble Bank in the Solent in January 2015, forcing emergency services to rescue all 25 crew members on board.