Country singer George Hamilton IV -- best known for the hit song 'Abilene' -- dies at 77

(CNN) -- Country singer George Hamilton IV, whose biggest hit "Abilene" reached No. 1 in the courty charts in 1963, has died at a Nashville hospital following a heart attack, the Grand Ole Opry said in a press release. He was 77.

Hamilton -- no relation to the actor George Hamilton -- was known as the "International Ambassador of Country Music."

His other country hits were "Before This Day Ends," "Three Steps to the Phone" and "If You Don't Know, I Ain't Gonna Tell You."

Hamilton performed around the world and became the first American country singer to appear in the Soviet Union and Czechoslovakia and was the first to record a studio album in Eastern Europe, the Grand Ole Opry said.

He performed extensively in Canada and recorded songs by Canadian songwriters such as Joni Mitchell and Gordon Lightfoot.

Hamilton started out as a pop singer and had a million-selling hit "A Rose and a Baby Ruth" in 1956 before switching to country. He'd been a member of the Grand Ole Opry since 1960.

The North Carolina native died Wednesday Saint Thomas Midtown Hospital in Nashville. Funeral arrangements have not been announced.