A boat owner was catapulted overboard when his moored cruiser exploded into flames in Littlehampton harbour.

Holidaymakers enjoying the sunshine watched in horror as the 26ft motor boat's cockpit was engulfed in flames.

Several men working in the busy harbour at lunchtime on Saturday went to help the man after he was flung over the stern of the boat by the blast.

David Beal, 62, was carrying out work on gangways and jetties with a team of men from Littlehampton Sailing and Motor Club when he heard the explosion.

He said: "We heard the noise and saw him go over the back end.

"It was really loud. Some of the guys went to help straight away."

Mr Beal, who is a boat owner himself and served in the Royal Navy for 35 years, grabbed a fire extinguisher while two of his colleagues went to pull the man from the water.

He said: "I got the extinguisher and pumped foam into it but it didn't touch it."

Mr Beal, who once witnessed a similar accident in which a man died, said he believed the blast could have been caused by fumes building up in the boat from either gas cylinders or the fuel.

Holidaymaker Sara Unwin, 44, from Sheffield, was another witness of the explosion.

She was in Littlehampton for the weekend with her partner and his grandfather, from Steyning.

She said: "We were looking across the river at the boats when there was this incredible bang and there was literally a ball of flame.

"I saw one guy appear to jump off at the end of the boat.

"It didn't take long before there was thick, black smoke and flames."

Sailors with boats moored nearby tried to move them from the vicinity of the burning boat.

Two fire crews from Littlehampton backed up by a specialist fire service boat went to the scene.

Littlehampton's RNLI lifeboat was also launched within minutes of the blast.

The crews cordoned off the area because of the threat of exploding gas cylinders as they protected nearby boats with cooling spray.

Incident commander Chris Bishop, of the West Sussex Fire and Rescue Service, said after the incident: "The owner was very lucky to escape as this fire could have had tragic consequences.

"We would urge all boat owners to check fuel lines are in good condition and seaworthy at all times."

The victim of the explosion was taken to hospital although his injuries are not thought to be life-threatening.