Country music star Johnny Cash is said to be in a "serious but stable" condition in hospital with pneumonia.

The Grammy-award-winning singer, known as the Man in Black, was admitted to Nashville's Baptist Hospital on Sunday.

Cash, who has suffered from repeated bouts of pneumonia, was diagnosed with Shy-Drager syndrome, an illness similar to Parkinson's disease, in 1997.

The singer has since said he was misdiagnosed, but continues to suffer from ill-health.

Cash, whose hits include A Boy Named Sue and A Thing Called Love, has sold more than 50 million records during a career spanning five decades.

Halls of fame

Born into a poor family in Arkansas in 1932, he claims to have only ever had one singing lesson, in which he was given the advice, "Never change your voice".

He has since lent his distinctive bass tones to songs of coal miners, convicts and cowboys.

He is the only person to have been inducted into the Rock and Roll Hall of Fame as well as the Country Music Hall of Fame and the Songwriters Hall of Fame.

In a life shadowed by drug and alcohol abuse and trouble with the law, Cash was once fined $85,000 (�58,000) for starting a forest fire.

Although he has not toured since 1997, he recently released a new album, American III: Solitary Man, nominated in January for two Grammies for Best Male Country Vocal Performance and Best Contemporary Folk Album.

The Grammys take place on 21 February.