Image copyright Getty Images Image caption David Olney released more than 20 albums during his solo career

The American singer-songwriter David Olney has died on stage during a performance at a festival in Florida.

The 71-year-old was mid-song when he apologised, closed his eyes and fell silent, two musicians who were performing alongside him said.

He suffered an apparent heart attack during the show in Santa Rosa Beach on Saturday night, a statement said.

Olney was a key member of Nashville's music scene and his songs were recorded by a number of country and folk stars.

In the early 1980s, he formed a rock band called The X-Rays before embarking on a solo career and releasing more than 20 albums.

"Olney was in the middle of his third song when he stopped, apologised and shut his eyes," Amy Rigby, a musician who was sitting next to him, wrote in a Facebook post.

"He was very still, sitting upright with his guitar on, wearing the coolest hat and a beautiful rust suede jacket," she added.

Scott Miller, who was also on stage with Olney, said he had attempted to revive the singer.

"David paused, said, 'I'm sorry' and put his chin to his chest," he wrote. "It was as easy and gentle as he was."

"We got him down and tried our best to revive him until the EMTs [emergency medical technicians] arrived. The world lost a good one last night but we still have his work. And it still inspires."

In a statement posted on Olney's website, Emmylou Harris, a member of the Country Music Hall of Fame, paid tribute to the singer's ability to tell "marvellous stories with characters who cling to the hope of enduring love".