Casey Kasem, the smooth-voiced US broadcaster who became the king of the top 40 countdown, has died at the age of 82.

Danny Deraney, publicist for Kasem's daughter, Kerri, said the star died on the morning of June 15.

Kasem's American Top 40 began on July 4, 1970, in Los Angeles. The number one song on his list then was Mama Told Me Not to Come, by Three Dog Night.

The show continued in varying forms - and for varying syndicators - until his retirement in 2009. In his sign-off, he would tell viewers: "And don't forget: keep your feet on the ground and keep reaching for the stars."

Ryan Seacrest said his death was a loss for radio listeners worldwide. Seacrest, who took over the countdown from Kasem in 2004, said in a statement that as a child, he'd listen to Kasem's show every weekend "and dream about someday becoming a radio DJ".

He said Kasem had a distinctive friendly on-air voice and would be greatly missed.

Kasem's legacy reached well beyond music. His voice was heard in TV cartoons such as Scooby-Doo, where he played Shaggy, and in numerous commercials.