Media playback is unsupported on your device Media caption Tributes for Olympic sailor Simpson

A British Olympic sailor has died after a Swedish catamaran capsized during a training session for the America's Cup in San Francisco Bay.

Andrew "Bart" Simpson - a double Olympic medallist - was one of an 11-man crew on board the Artemis Racing catamaran, the team website said.

It said Mr Simpson, 36, from Sherborne in Dorset, was trapped under the boat and efforts to revive him failed.

Artemis is a Swedish team due to take part in the America's Cup.

On its website, Artemis Racing said: "It is with immense sadness that Artemis Racing confirms the tragic death of crewmember Andrew 'Bart' Simpson today in San Francisco."

At a news conference by the Bay, Artemis chief executive Paul Cayard said it was a "tragic day" for the crew.

"We have a lot to deal with in the next few days in terms of assuring everybody's wellbeing," Mr Cayard said, as he offered his thoughts and prayers to Mr Simpson's wife and family.

[Andrew Simpson was] a fantastic sailor who got the best out of everyone he sailed with Stephen Park, RYA Olympic Manager

Mr Simpson represented Great Britain at two Olympic Games, sailing in the Star class alongside Iain Percy, his Artemis team boss.

The pair took gold at the Beijing 2008 Games and were close at London 2012 to topping the podium once more, only to claim silver in the medal race.

Before last summer's Olympics, Mr Simpson admitted that winning the America's Cup was his biggest goal.

Cause unclear

John Derbyshire, performance director of the UK's Royal Yachting Association (RYA), described Simpson as an inspiration to others.

"We're devastated by the news from San Francisco today," he said.

"Andrew is someone I've worked closely with since the age of 16. He was a great talent and a key figure in our World Class Programme over many years culminating in his well-deserved Olympic success.

"He was a huge inspiration to others, both within the British Sailing Team and across the nation and our deepest sympathies go out to his family at this terrible time."

Media playback is unsupported on your device Media caption Paul Cayard: "It's a shocking experience to go through"

Stephen Park, RYA Olympic Manager, described Mr Simpson as "a fantastic sailor who got the best out of everyone he sailed with".

Artemis said that doctors "afloat" with the team tried unsuccessfully to revive the British sailor after he was freed from the wreckage.

San Francisco Fire Department spokeswoman Mindy Talmadge said that, following the capsize, two sailors were brought to shore and taken to the St Francis Yacht Club where paramedics performed CPR on one of them.

The other person's injuries were not life-threatening, she said.

The rest of the crew from the capsized boat were transferred to a support boat operated by Oracle Racing, which is defending its America's Cup title from last year, officials said.

Mr Simpson served as the Swedish team's strategist.

Lt Jeannie Crump of the Coast Guard said it was not yet clear what caused the 72ft (22m) boat to capsize.

She said that a commercial salvage boat would tow the vessel to Clipper Cove, between Yerba Buena Island and Treasure Island.

The America's Cup is inshore yachting's premier event, and will take place in San Francisco this year between July and September.

Multi-million pound syndicates use cutting-edge design and technology as the world's best sailors battle it out for the oldest trophy in sport.

The first race for The "Auld Mug" took place around the Isle of Wight in 1851.

US yacht America won to spark 132 years of US domination until Australia II broke the deadlock in 1983.

Simpson is believed to be the second sailor to have died during training for the race.

In 1999, Martin Wizner of the Spanish Challenge was fatally injured after being struck on the head by a broken piece of equipment.