A 14-year-old Sea Cadet died after falling overboard from a ship off the Hampshire coast, police said today.

The boy was airlifted to hospital by coastguard helicopter following the incident in Stokes Bay, near Gosport, yesterday evening but was later pronounced dead.

It is thought he fell up to 30 feet fromt he ship into the sea while climbing the rigging. A Hampshire Police spokesman said he was one of a number of Sea Cadets on board the training ship TS Royalist.

He said: ''The Marine Accident Investigation Unit is currently investigating the circumstances surrounding the death of a 14-year-old boy which occurred in the Solent yesterday evening, Sunday May 2.

''The Marine Accident Investigation Unit and Hampshire Constabulary are fully reviewing all of the circumstances surrounding the death and the coroner has been notified.''

Police said the boy was from Kent.

Detective Inspector Andy Symes from Gosport CID said: ''The ship had sailed out to Stokes Bay when at around 8.30pm yesterday the boy fell from rigging into the water.

''He was recovered by lifeboat and taken by helicopter to the Queen Alexandra Hospital, Cosham, where he was pronounced dead.

''The boy's parents have been notified.''

Solent Coastguard said it received a Mayday call from the ship at 8.30pm stating that a member of the crew had fallen over the side while it was at anchor in Stokes Bay.

The Coastguard Rescue helicopter attended the scene along with the Gosport and Fareham Inshore Rescue Service.

Colin Griffiths, watch manager at Solent Maritime Rescue Coordination Centre, said: ''The crew member fell overboard and was recovered by the sail training Rib (rigid inflatable boat) and transferred to the lifeboat.

''The casualty was then taken by rescue helicopter to the landing site for the Queen Alexandra Hospital.''

A Sea Cadets spokeswoman said the accident is believed to have happened while the ship's sails were being stowed.

The ship returned to shore after the incident and the remaining youngsters disembarked to be reunited with their families.

The 19 cadets and 10 staff set off on the training exercise on Friday and were meant to return a week later.

Yesterday, the Sea Cadets celebrated 150 years of the movement with displays and demonstrations at Gunwharf Quays in Portsmouth harbour.

The spokeswoman said the girls and boys on board the Royalist were part of the event.

A statement released by the Marine Society & Sea Cadets said it was the first death the ship has experienced since she was commissioned in 1971.

The statement said: ''The charity is deeply saddened to report that a tragic and fatal accident occurred on Sea Cadet training vessel TS Royalist on Sunday May 2 2010.

''Our thoughts are with the young cadet's family at this distressing and painful time.

''The charity is now working with the Maritime Accident Investigation Branch to establish the full details of what happened and offering every assistance to the local authorities and police.

''The protection and safeguarding of young people is of paramount importance to the charity, and we take our duty of care very seriously. TS Royalist is staffed by experienced and qualified crew.''

The voluntary youth organisation is open to young people aged 12 to 18 but members must be at least 13-and-a-half to go to sea.

Marine Society & Sea Cadets chief executive Mike Cornish said the boy fell from a height of around 20ft to 30ft into the sea from the starboard side of the ship.

He would have been wearing a safety harness but the cadets did not wear lifejackets when climbing the rigging in case they got tangled up.

He said: ''At this particular juncture, all we can say is that the captain took the Royalist out of the harbour at the end of the Sea Cadet Festival at Gunwharf Quays and took it to Stokes Bay, not very far away, for anchorage.

''The cadets were ordered to furl and reef the sails, which is standard operational procedure for the night and unfortunately the cadet fell while aloft.''

Mr Cornish described the incident as an ''extremely tragic accident'' and said it was ''appalling for all those involved''.

''The cadets are fully trained and will only climb the rigging if comfortable with climbing,'' he added.