A Kent couple are among six missing tourists authorities are looking for after a luxury yacht was sunk by a tornado off the coast of Italy.

Divers are searching for a British tycoon and Sevenoaks couple Jonathan and Judy Bloomer after the vessel was hit by a storm at around 5am on Monday.

One person, believed to be the yacht’s chef, died onboard while 15 of the 22 passengers were rescued from the waters near Porticello.

The Bloomers, as well as tycoon Mike Lynch, his daughter Hannah Lynch, Clifford Chance lawyer Chris Morvillo, and his wife Neda Morvillo still haven’t been found.

Mr Bloomer is the chairman of Morgan Stanley International Bank and lives in Sevenoaks.

His twin brother, Jeremy Bloomer, said the family haven’t received any updates but have their fingers crossed they are both found, the BBC reports.

He added: “I'm just numb, just numb. That's it, you don't know what to think and you can't believe it's happened."

A spokesman for 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.

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.

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 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”.

An Italian newspaper reported 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.