A frantic search for survivors is underway after a luxury yacht with 22 people, including Britons, on board sank in the early hours off the coast of Sicily after being hit by a tornado.

Italian authorities mobilised en masse around 5am this morning (Monday) after the stricken vessel began to capsize following a freak weather event. 

The luxury 180-foot yacht features the second tallest mast in the world and was photographed just last night moored on apparently calm waters some 300 metres from the harbour at Porticello, near the Sicilian capital Palermo.

In the image posted on a local Facebook page the yacht, named as British-flagged The Bayesian, looked serene with lights from the ship reflected from the sea just hours before tragedy struck.

Latest reports say a woman and one-year-child are among 15 people rescued, but one person has been confirmed dead and a further six are still unaccounted for. 

Express.co.uk explores what we know about the tragedy so far... 

The vessel named in the tragedy is the Bayesian, a British-flagged ship which was reportedly carrying 22 people on board at the time of the tragedy. 

Website Marine Traffic describes the Bayesian as a sailing vessel under the flag of the United Kingdom. Her overall length is reported as 183 feet and her width is recorded as 37 feet.

The shipping site Yacht Harbour says the Bayesian was built in 2008 and has a gross tonnage of 473 tons powered by engines capable of a maximum speed of 15 knots. 

The website adds that "Bayesian's maximum range is estimated at 3600 nautical miles" and it "can accommodate 12 guests in 6 cabins". 

The ship, which reportedly costs £173,000 per week to charter, also has the second-tallest mast of a vessel of its kind in the world, at 246 feet.

At least one person has so far been confirmed dead and a further six are still unaccounted for after the ship capsized around 4am local time off the coast of Porticello, near the Sicilian capital Palermo, Italy.

Italy's fire and rescue service Vigili del Fuoco said in a post on X earlier today (Monday) that a rescue operation from dawn involved "Vigili del Fuoco engaged in the search. Wreck identified at 50 metres depth, speleo divers arriving".

Filippo Tripoli, the mayor of Porticello, has updated the public on the situation with a post on social media saying that Red Cross volunteers are aiding in the search for the seven missing people.

He said: "This morning off the coast of Santa Flavia a foreign boat sunk due to bad weather, 15 people recovered and seven were missing.

"Already all the police forces and emergency services are operational, our Red Cross volunteers are present and the availability of other civil protection associations of the territory has been asked, alerted by the regional civil protection department."

A Dutch-flagged vessel called the Sir Robert BP has been credited with saving the lives of 15 people on board the Bayesian, including a woman and one-year-old child who are stable in hospital. 

According to local reports weather forecasters "did not report this kind of event" in terms of a tornado warning. A woman posting on social media added: "The weather [forecaster] didn't report these kind of events, nor strong winds... last night everything was still. Nobody expected a tornado."

La Sicilia reports some witnesses said the Bayesian was still at anchor in front of the port of Porticello when the tornado struck and that the huge sail mast was broken leading to the ship becoming unbalanced. 

A man from Porticello told the paper: "That vessel was all lit up, at about 4.30am in the morning it was gone. A beautiful vessel where there had been a party. A normal holiday day spent happily at sea turned into a tragedy.

"The vessel was not far from the port. It would have taken very little to raise the anchor and head for the port. Evidently they were surprised by the storm that suddenly hit and they were unable to avoid the sinking."

The strong winds around the Sicilian island come as earlier this month tornado weather events struck the Spanish island of Majorca elsewhere in the Mediterranean causing havoc for local boats at sea. 

And in Sicily in March a tornado was reported by La Sicilia as hitting Birgi Airport with winds of up to 93mph.