Captain Karsten Borner has recalled the tragic moments he witnessed the capsizing of a luxury yacht after it was struck by an unexpectedly violent storm and sank off the Sicilian capital Palermo.

Search and rescue operations were under way on Monday 19 August after one man died and six people were missing after a 56-meter-long (184-ft) sailboat, which was British registered, sank with 22 people on board shortly before sunrise.

British technology tycoon Mike Lynch is missing after the luxury superyacht sank, sources have said.

The yacht had a crew of 10 people and 12 passengers, representing British, American and Canadian nationalities, the Italian coast guard said.

The coastguard named the yacht as the Bayesian, built by Italian shipbuilder Perini in 2008.