Two members of the Italian powerboat team had to be rescued when their craft exploded off Brighton beach during the British Grand Prix.

Thousands of spectators watched in shock as the vessel - throttled by retired international rugby star Toto Gualdambrini - burst into flames just 200 yards from the shore.

Gualdambrini, 47, and his driver, Lucio Stefani, had just been pulled from the boat before the fire took hold and ripped through the bow, sending thick plumes of smoke into the air which could be seen five miles away The Italian Flaminia Supersport boat, built for a six-figure sum, was competing on Saturday in the British leg of the Powerboat P1 World Championships, taking place in Brighton for the first time.

It was powered by two 275bhp Mercury XR2 engines, which guzzle an average of 200 litres of fuel an hour. It is thought the fuel tank ignited after an electrical fault.

Father-of-four Gualdambrini and Stefani were not hurt.

A spokesman for the race promoter, KBL Management, said: "They are high-powered boats with fuel on board and it is an adventure sport."

A rescue boat reached Flaminia, carrying 500 litres of fuel at the start of the race, as it was seen to be in trouble. It was taken in tow but as the fire blazed it had to be cut loose and drifted safely to shore under supervision at Hove beach.

Stephen Cotterell, 48, a business consultant, of Preston Drove, Brighton, was watching the event with friends and family when the fire started.

He said: "It stopped and an emergency boat came and took the crew off.

"I saw loads of smoke, which seemed to get darker and darker.

"Then there were these amazing orange flames. There was quite a crowd of people watching and some were panicking a bit, wondering if people were still on the boat."

Crowds gathered at Brighton Marina to watch as the boats headed out for the Endurance race - a course of 84 nautical miles for the bigger Evolution category boats and 71 nautical miles for the smaller SuperSport category.

Each Evolution-class boat is powered by twin engines capable of producing 2,000 bhp and reaching speeds in excess of 90mph.

The strong wind over the weekend meant the seas were treacherously choppy.

Watching from the corporate village at the marina with other VIPs was model and presenter Alex Best, along with Brighton businessman Howard Kruger.

Dressed in a floral print skirt, a pink top and strapless high heels, Alex, 32, said: "It is absolutely fabulous. This is the first time the grand prix has been held in Britain so I am happy to support it.

"I love adrenalin sports. I have been powerboating and I have also parachuted off the side of a mountain. I just think that sort of thing is fun."

Although she lives in Reigate she is a regular visitor to Brighton, spending two nights a week in the city.

Her work will bring her to Sussex even more regularly as she is about to star in a publicity campaign for Toni and Guy's latest salon.

She said: "I love the sea and I love Brighton. I like shopping down in The Lanes and I like the nice restaurants."