British technology tycoon Mike Lynch and five others are feared to have died, with their bodies trapped inside a luxury yacht which sank in a tornado.

Vincenzo Zagarola of the Italian Coastguard said this was the working theory of officials on Sicily because it is believed the boat sank quickly and search and rescue efforts by sea and air have so far delivered no results.

He told the PA news agency: “We think they are still inside the boat, that is our very hard idea.

“Our search and rescue activity by sea and air has gone on for around 36 hours.

“Of course, we do not exclude that they are not inside the boat, but we know the boat sank quickly.

“We suppose that the six people missing may not have had time to get out of the boat.”

Asked about the likelihood of them being alive, he replied: “Never say never, but reasonably the answer should be not.”

Bayesian was moored around half-a-mile off the coast of Porticello when it sank at around 5am local time on Monday as the area was hit by a storm.

The missing tourists are: Mr Lynch; his daughter, Hannah Lynch; Morgan Stanley International bank chairman Jonathan Bloomer; his wife, Judy Bloomer; Clifford Chance lawyer Chris Morvillo; and his wife, Neda Morvillo.

Italy’s fire brigade Vigili del Fuoco said it is developing a plan to enter the wreckage of Bayesian, which is resting on the seabed off the coast at a depth of 50 metres.

It described the operation as “complex”, with divers limited to 12-minute underwater shifts.

A spokesperson for Latymer Upper School in Hammersmith, west London, where Hannah Lynch was a former pupil, said in a statement: “We are all incredibly shocked by the news that Hannah and her father are among those missing in this tragic incident and our thoughts are with their family and everyone involved as we await further updates.”

Fifteen of the 22 passengers and crew onboard – including Mr Lynch’s wife, Angela Bacares – were rescued after escaping onto a lifeboat.

On Tuesday, an inflated orange lifeboat was docked at the harbour near where search crews are being dispatched.

One body, reportedly belonging to the ship’s chef, was recovered at the scene of the sinking on Monday.

Mr Lynch, who founded software giant Autonomy in 1996, was cleared in June of conducting a massive fraud relating to an 11 billion US dollar (£8.64 billion) sale to US company Hewlett Packard.

The boat trip was a celebration of his acquittal.

The Financial Times reported that Mr Bloomer appeared at trial as a defence witness for Mr Lynch, while media reports suggest the pair are close friends.

A spokesperson for Morgan Stanley said the bank was “shocked and saddened” while Clifford Chance said it was a “tragic incident”.

Ed Llewellyn, British ambassador to Italy, met some of the survivors of the sinking at a hotel.

He said: “I’ve spoken to some of the British survivors both yesterday and today – I want to express my deep sympathy from myself and colleagues at the British embassy for what’s happened.

“We’re doing what we can to support them in this incredibly sad and difficult situation to help them with contacts from the Italian authorities at a practical level.”

Ayla Ronald, a New Zealand national working at Clifford Chance, survived the ordeal.

Her father Lin Ronald confirmed to the Telegraph she had been invited aboard as a thanks for assistance in Mr Lynch’s recent court case.

“I have texted my daughter and she hasn’t given me any updates about missing personnel or saved personnel. She has only said that there are deaths and she and her partner are alive,” he said.

“Ayla is a lawyer who is part of the legal team that were invited to go sailing as a result of the success in the recent United States court case.”

One of the survivors, British tourist Charlotte Emsley, told la Repubblica she held her one-year-old daughter, Sofia, to stop her from drowning.

Charlotte and Sofia were treated in hospital, as was Sofia’s father, James Emsley.

The Marine Accident Investigation Branch said four of its inspectors have been deployed to Palermo.

Mr Lynch’s co-defendant Stephen Chamberlain died after being hit by a car while out running in Cambridgeshire on Saturday.

In a statement released through Cambridgeshire Police, Mr Chamberlain’s family said: “Steve was a much-loved husband, father, son, brother and friend.

“He was an amazing individual whose only goal in life was to help others in any way possible.”