British Olympic champion Andrew 'Bart' Simpson has died after his yacht capsized off the California coast during training for the America's Cup race.

Mr Simpson won a gold medal at the 2008 Beijing games and a silver medal in London in 2012.

He had been sailing on the Artemis, Sweden's entry in the America's Cup, when the catamaran capsized off San Francisco, according to a statement on the Artemis racing website.

"The entire Artemis Racing team is devastated by what happened," said CEO Paul Cayard.

"Our heartfelt condolences are with Andrew's wife and family."

The America's Cup race is due to begin in July.