He became an icon of American country music from the 1950s, with songs such as I Walk the Line and Ring of Fire.

His wife June Carter Cash, with whom he had recorded many songs, died earlier this year following complications from heart surgery.

"Johnny died due to complications from diabetes, which resulted in respiratory failure," manager Lou Robin said in a statement. "I hope that friends and fans of Johnny will pray for the Cash family to find comfort during this very difficult time," he added. In recent years, Cash had also suffered from Shy-Drager, a condition similar to Parkinson's disease which attacks the nervous system and affects muscle control.

Cash was regarded as one of the most important figures in country music, in a career that spanned six decades. He became as famous for his image as an outlaw figure, for playing in prisons and creating the myth of the Man in Black, his semi-official nickname.

Cash's albums included Folsom Prison Blues, a 1968 live album recorded at a jailhouse concert. Cash, who sang in a gruff, baritone voice, had hits in the 1960s with Ring of Fire and A Boy Named Sue. He finished live touring in 1997, but continued recording albums.

Cash became popular with a new audience of music fans with his American Recordings, which covered contemporary artists. Cash became a sensation with the MTV generation for his covers of songs such as Depeche Mode's Personal Jesus, U2's One, and Nick Cave's The Mercy Seat across four of his most recent albums.

This year, the video for his cover of hard rock band Nine Inch Nails' Hurt received critical acclaim and many nominations at the MTV Video Music Awards last month.

Cash was born in Arkansas in 1932, and started writing his own songs at the age of 12, influenced by country songs he heard on the radio. In 1957 he became the first artiste on the influential Sun record label to release a full album, beating Elvis Presley. In the 1960s his gruelling schedule of over 300 live shows led to him becoming addicted to amphetamines. His drug abuse led to the collapse of his first marriage to wife Vivianne.

In the mid '60s he met June Carter Cash, one of country's famous Carter family. She co-wrote Ring of Fire, giving him a top ten hit, and the pair married in 1968.

During his career, Cash won 11 Grammy Awards, most recently a Best Male Country Vocal Performance for Give My Love to Rose.