US singer Isaac Hayes dies aged 65

The Shelby County Sheriff's Office said a family member found Hayes unresponsive near a treadmill on Sunday. He was pronounced dead about an hour later at Baptist East Hospital in Memphis.

The cause of death was not immediately known.

In the early 1970s, Hayes laid the groundwork for disco, for what became known as urban-contemporary music and for romantic crooners such as Barry White. He was rapping before there was rap.

His career hit another high in 1997 when he became the voice of Chef, the sensible school cook and devoted ladies man on the animated TV show South Park.

The album Hot Buttered Soul made Hayes a star in 1969. His shaven head, gold chains and sunglasses gave him a compelling visual image. The album was groundbreaking in several ways - he sang in a "cool" style unlike the usual histrionics of big-time soul singers. He prefaced the song with "raps," and the numbers ran longer than three minutes.

Next came Theme From Shaft, a No. 1 hit in 1971 from the film Shaft, starring Richard Roundtree. "That was like the shot heard round the world," Hayes said in the 1999 interview.

At the Oscar ceremony in 1972, Hayes performed the song wearing an eye-popping amount of gold and received a standing ovation. TV Guide later chose it as No. 18 in its list of television's 25 most memorable moments. He won an Academy Award for the song and was nominated for another one for the score. The song and score also won him two Grammys.

Hayes was elected to the Rock and Roll Hall of Fame in 2002.

"I knew nothing about the business, or trends and things like that," he said. "I think it was a matter of timing. I didn't know what was unfolding."