Italian prosecutors will investigate the captain of the superyacht belonging to British tech magnate Mike Lynch that sank off Sicily last week during an intense storm, killing Lynch and six other people, Italian media reports said on Monday.

Being placed under investigation in Italy does not imply guilt and does not mean formal charges will necessarily follow.

James Cutfield, a 51-year old New Zealand national, is being investigated for manslaughter and shipwreck, the dailies La Repubblica and Corriere della Sera said.

Magistrates spoke to Cutfield on Sunday for the second time in a week, la Repubblica reported, questioning him for more than two hours. It said prosecutors may also investigate a crew member who was on duty when the storm hit and survived the incident.

The British-flagged Bayesian, a 56-metre-long (184-foot) superyacht, was carrying 22 people when it capsized and sank on Monday within minutes of being hit by a pre-dawn storm while anchored off northern Sicily.

Fifteen people survived, including Lynch's wife, whose company owned the Bayesian. Lynch's 18-year-old daughter, Hannah, was among those who died.

While the yacht had been hit by a sudden meteorological event, it was plausible that crimes of multiple manslaughter and causing a shipwreck through negligence had been committed, the head of the public prosecutor's office of Termini Imerese, Ambrogio Cartosio, said on Saturday.

Maritime law gives a captain full responsibility for the ship, crew, and all on board.

Cutfield and his eight surviving crew members have made no public comment yet on the disaster.

"The Bayesian was built to go to sea in any weather", Franco Romani, a nautical architect that was part of the team that designed it told daily La Stampa in an interview published on Monday.

He said it was likely the yacht had taken on water from a side hatch that was left open.

Romani said the crew underestimated the bad weather and that they should have made sure that all openings had been shut and the anchor removed before the storm hit the boat.