Police divers searching for British technology tycoon Mike Lynch and five others who were on a luxury yacht which sank in a tornado are trying to access the ship’s cabins.

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 of Sicily at a depth of 50 metres.

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

Rescue crews said they assume the six missing tourists will be found in the cabins, which they were unable to enter on Monday due to debris.

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

Civil protection officials believe the yacht was battered by a tornado over the water, known as a waterspout.

Local fisherman Giuseppe Cefalu told the PA news agency through a translator that he saw a “tornado” close to the port of Porticello, and he and his brother Fabio saw a flare in the sky at around 5am.

The pair aided efforts to locate people in the water after the yacht sank, but Mr Cefalu said he only saw cushions and a buoy.

He said weather conditions on the morning of the sinking were “fierce”, with “very strong” wind and rain.

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

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

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 appears to have been a celebration of his acquittal.

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.

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.

The British ambassador to Italy, Ed Llewellyn, 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.”

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

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.”

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.”

The daily Il Giornale di Sicilia newspaper reported that the vessel had mostly British passengers on board, but also people from New Zealand, Sri Lanka, Ireland and British-French citizens.

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

She said: “I held her afloat with all my strength, my arms stretched upwards to keep her from drowning.

“It was all dark. In the water I couldn’t keep my eyes open. I screamed for help but all I could hear around me was the screams of others.”

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.