Two people were rescued by lifeboat when an on-deck barbecue set their cabin cruiser ablaze off the Sussex coast.

Two people were rescued from the Sirron amid fears the on-board fuel tanks were about to explode.

Onlookers then heard loud bangs after gas canisters ignited and rescue crews thought more could blow up.

The cruiser caught fire less than half a mile from the shore, just west of Rottingdean harbour, shortly after 2.30pm yesterday.

Witnesses described hearing several bangs before seeing smoke and flames billowing from the 30ft-long cruiser.

Her crew were taken to safety within minutes of the first emergency calls and watched from the deck of another boat as flames gutted the hull.

Lifeboat teams declared a half-mile exclusion zone to other shipping as black smoke shrouded the craft.

Crews from Brighton Lifeboat and Newhaven Lifeboat struggled to get near because of the raging blaze.

After an hour they were able to pull close enough to start to douse the flames.

A lifeboat spokeswoman said: "There were two explosions of canisters with the possibility of another couple going."

Crews from Roedean fire station were called. They were about to go on board until they were alerted to the presence of the cylinders.

Firefighter Steve Doidge said: "At first the fire didn't seem so bad and the lifeboats were going to tow her in.

"But we realised it would be safer to move everyone back a safe distance. There was no risk to lives but if we'd gone nearer there certainly would have been."

Dave Crowhurst, 36, from Saltdean, was among a crowd of onlookers who gathered on the beach.

He said: "The boat started burning very badly pretty quickly, with lots of red and black smoke. Anyone on board had a lucky escape."

Joe Dore, 18, said: "Everyone was crowding around on the shore, thinking it was going to blow. The air was filled with thick smoke."

David Landau, from Peacehaven, said: "I was parking my car nearby when I heard two loud explosions.

"I went to have a look and all I could see was a huge pall of smoke pouring out of this boat."

Argus columnist Dr David Delvin saw the fire from a hill almost a mile away.

He said: "There was so much smoke you could tell the boat was seriously affected.

"Other boats came to help but they couldn't get near for a while because the fire was so bad."

Once the fire was under control, the smouldering hulk was towed into Brighton Marina.