Media playback is unsupported on your device Media caption Moment helicopter crashes in fjord in Bergen

Three Britons have been injured - one seriously - after a helicopter fell from a superyacht in Norway.

The helicopter lost control when a tarpaulin got entangled in its rotors as it tried to land on a luxury yacht in Bergen on Wednesday, Norwegian investigators say.

Haukeland University Hospital confirmed it was treating a 57-year-old man, who is in a critical condition.

The other two hurt suffered what have been described as "minor injuries".

The pair were released from hospital on Thursday and the Foreign Office said it was assisting all three Britons.

An investigation into the incident has found that a loose fuel tank cover was sucked into the helicopter's rotors as it attempted to land.

The pilot tried to avoid it but the helicopter span out of control, landing upside down in the water, according to a statement from the Norwegian Accident Investigation Board on Friday.

British air safety investigators are assisting their Norwegian counterparts.

Image copyright Oddgeir Øystese/NRK Image caption The helicopter is hoisted out of the fjord after the crash in Bergen

Reports suggest that the helicopter was owned by HQ Aviation, based at Denham Aerodrome, in Middlesex, and had refuelled in Shetland before flying to Norway.

The 195-foot (59m) Bacarella, currently moored in Bergen, was sold for over £23 million at auction in 2014.

'It just plunged'

Kara Lynsdale, from London, saw the incident unfold from a tall ship in Bergen harbour.

Image copyright Oddgeir Øystese/NRK Image caption The Bacarella superyacht, pictured after Wednesday's crash

"It almost looked like it rolled off the boat, or hadn't landed properly on the boat and missed it," she said.

"It fell from such a low height that it just plunged - it sank straight away."

Miss Lynsdale said she saw lifeboat crew trying to resuscitate someone as they took them across the harbour.

"It was quite shocking to see them bomb past giving someone CPR in the back of the boat," she said.

Image copyright Ronnie Robertson Image caption The helicopter refuelling in Shetland before flying to Bergen

Bergen resident Jan Haughland was taking photographs of a tall ship on the fjord when he heard a "crash and splash in one".

He said up to five boats raced to the scene, including a passing passenger ferry that was diverted from its course.

"It can't have been more than five minutes before they arrived, it all happened very fast," he said.