Edward Guinness will be investigated by Italian police after his boat struck rocks on Lake Como and sank, injuring five passengers

The heir to the Guinness family fortune is due to be investigated by Italian police, after his boat sank on Lake Como.

Edward Guinness is thought to have been at the helm at 3:30am on Sunday 3 May when a boat carrying ten people hit a rocky outcrop and sank, just 150-metres from the dock.

Five people were taken to hospital with serious injuries and the incident has been referred to local deputy prosecutor Pasquale Addesso, according to local publication Corriere Della Sera.

Divers will be sent into Lake Como to retrieve the wreck, which sank to a depth of 300 metres below the surface. Preliminary investigations suggest the boat was traveling at high speed at the time of impact.

Edward, 39, is one of the direct descendants of Arthur Guinness, who founded the Dublin-based stout brewing business in 1759.

He was among the five people hospitalised for fractures and bruises, but was discharged last Tuesday (May 5).

Spanish actress Natalia de Azcarate was also among those injured, and she is expected to be hospitalised for around two months.

The group of English and Spanish tourists aged between 36 and 48 were visiting Lake Como (pictured above) to celebrate a birthday, the local newspaper adds.