The Italian coast guard on Thursday said the body of British tech magnate Mike Lynch was among those recovered off the coast of Sicily from the wreckage of a superyacht.

One woman remains missing.

The bodies of Lynch, who had been celebrating his recent acquittal on fraud charges with his family and the people who had defended him at trial in the United States, and five others were recovered by rescue crews following Monday's tragedy.

The Bayesian, a 56-metre British-flagged yacht, went down in a storm early Monday as it was moored about a kilometre offshore. Civil protection officials said they believe the ship was struck by a tornado over the water, known as a waterspout, and sank quickly.

Investigators are now looking at why the Bayesian sank, killing at least six people. A seventh remains missing.

Fifteen of the 22 people aboard survived, including a mother who reported holding her one-year-old baby over the waves to save her.

Divers have struggled to find the bodies in the yacht’s hull on the seabed 50 metres underwater.

“We would need a crystal ball to know when we'll be able to find the next body," said Luca Cari, spokesperson for the fire rescue service.

“It's very difficult to move inside the wreckage. Moving just one metre can take up to 24 hours,” Cari said. (AP)