Missing Morgan Stanley boss Jonathon Bloomer's twin brother has said it is still a 'wait and see' situation as hopes of finding him and his wife alive in the Sicily superyacht tragedy fades.

Six people including Mr Bloomer, his wife Judy, British tech tycoon Mike Lynch and his 18-year-old daughter are still missing after the £30million Bayesian superyacht capsized early yesterday morning.

Rescuers are now frantically searching for trapped survivors and have warned that the next 24 hours are 'critical' if there is to be any hope of finding anyone alive, with the distant possibility there could still be an air pocket inside the wreck.

Jeremy Bloomer has said his family is 'coping the best we can' and has not received any new updates on the search efforts, beyond that divers are struggling to access the wreck of the boat.

He told the BBC the situation is 'terrible' and something that's 'beyond your wildest imagination'.

He added: 'It's a slow process and it will take time. So there might be air pockets, but we don't know.

'He was my older [brother] by half an hour. So it means a lot when you lose a twin brother. It's still wait and see, so fingers crossed.

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

Locals of Knockholt in Kent, where Mr Bloomer and his wife used to spend weekends in a £5m country house on the edge of the picturesque village, also said they were stunned by the news.

Harry Osenton, who managed the local pub The Three Horseshoes where the couple would occasionally be seen, said: 'It is quite a shock. I remember he [Mr Bloomer] would come in here occasionally with his family. I don't think he lived in the village full time but was in here at the start of the summer.'

Neighbours to couple's large country house that has a separate cottage in the extensive grounds also expressed their shock.

They said: 'We have been following on the news and saw Johnathan's name. He mostly used the place at the weekends. I guess it was his country home and he lived in London most of the time.'

Others in the village said they had been following developments in the tragedy but did not know Mr Bloomer.

'I feel dreadfully sorry for his family,' said a resident who asked not to be named. 'I cannot imagine what they must be going through.'

Mr Bloomer, 70, was chairman of the international arm of the US banking giant Morgan Stanley. His country home was formerly a children's home from 1954 to 1965.

Search teams in Sicily say the boat he was on with his wife is marooned 164ft below the surface on the seabed and is so deep that dive teams can only go down for 10 minutes at a time, with their efforts being hampered by furniture blocking the entrances.

One expert has claimed that the ship, which is almost completely intact despite not being 'anchored in a safe place' before it sank, could have trapped pockets of air inside that might allow survivors to stay alive after the 'unprecedented' disaster.

There have been instances in the past of people surviving for days underwater in these circumstances, but rescue divers have warned that they are prepared to find bodies instead of living, breathing survivors.

One person is confirmed to have died after the £30million superyacht was struck by a terrifying waterspout at around 5am on Monday morning, with the ship's captain emotionally claiming 'we didn't see it coming' from his hospital bed.

It is believed the ship sank after its mast - one of the tallest in the world at an enormous 246ft-high - snapped during the brutal incident and keeled over, taking the hull beyond the 'down-flooding angle', according to nautical experts.

Divers attempting to get inside the superyacht have found their progress impeded with furniture blocking the entrances and exits.

Those in charge of the operation say the specialist divers are struggling to reach the cabins where survivors might be and are having to drill their way into the lounge.

Luca Cari, head of emergency communications for Italy's fire and rescue department, said divers can see nothing inside the yacht from the outside and have only been able to inspect the bridge deck - the room from which the captain navigates.

Describing the challenges faced by the divers, she told local news agency Ansa: 'They can stay underwater for a maximum of 12 minutes, two of which are needed to go up and down. So the real time to be able to carry out the search is 10 minutes per dive.'

Rescuers said that from what they can see, there appears to be no bodies on the bridge of the yacht, and divers are now working to break into the lounge area.

The boat is resting on the seabed on its starboard (right hand) side, 164ft below the waves, and the first efforts of the dive teams were unsuccessful in moving furniture impeding their access to the cabins below, said Insp. Tilotta.

The rescuers still hope that survivors might be found, against all odds, in trapped air pockets, but Insp Tilotta admitted 'it is a race against time and the quality of the oxygen will be bad'.