UPDATE: A drugs search was being carried out on the yacht of the Dutch man who fell to his death in St Mary's Harbour on the Isles of Scilly.
The 62-year-old's yacht the Windrose had been towed into the Isles of Scilly on Monday after the skipper reported he was suffering from fatigue and his rigging was failing "on the lee side of the mast" on Sunday.
Border Force officers were reported to have been removing items from the yacht's cabin.
The yacht has now been towed to Newlyn.
UPDATE: Police say that at approximately 8.30pm on Monday evening, Devon and Cornwall Police were alerted that a man was seriously injured after falling from the mast of a yacht. He later died in hospital from his injuries.
The man is believed to be a Dutch national in his early sixties.
It is understood that the yacht had been boarded as part of a Border Force (formerly UK Border Agency) operation shortly before the incident.
The matter has been referred to the IPCC by the Border Force and a local investigation will be carried out this morning.
A Border Force spokesman said: “We are assisting Devon and Cornwall Police with their investigation and the incident has been referred to the IPCC.”
It is unclear whether the yacht was boarded as part of an anti-smuggling operation.
The BBC are reporting that the skipper reported he was suffering from fatigue and his rigging was failing "on the lee side of the mast" on Sunday.
Adding that two RNLI crew boarded the 11m (36ft) yacht, Windrose and towed it into the Isles of Scilly.
UPDATE: St Mary's quay has reopened.
One person is reported to be dead after an incident on a boat in the Isles of Scilly last night.
The UK Border Agency are believed to be involved with police also investigating, however details are sparse at the moment
The twitter account for St Mary's Harbour said: "Harbour staff are facilitating the police with their investigation and will endeavour to open the quay fully as soon as we can.
"Access to the quay remains restricted this morning as a result of a police investigation into an incident yesterday evening."
The BBC are reporting that Falmouth Coastguard say an injured person was airlifted to the Royal Cornwall Hospital from the quay at St Mary's last night.