Coldplay star Chris Martin caused a stir by singing a tribute to Mariah Carey's breasts in front of a stunned American audience.

The ‘Clocks’ rocker was being questioned by US journalists as to whether Carey was a threat, as her album The Emancipation of Mimi was the best-selling album of last year (05).

The inspiration for the song came when a reporter asked Martin if he thought Carey was "on his tail" for the bestselling album of 2005.

The star, who was giving a private concert for winners of a radio contest, joked: "She's not, but one of her boobs is. They do most of her work. Last week I was chased down the street by an enormous boob. I think it was hers."

"Mariah Carey's boobs are so nice, and she doesn't mess around. If she had been aboard the Titanic, there's no way that ship would have gone down."

Martin added, "Man's been travelling through space and man's been to the moon and man's spent most of his intelligence desiring Mariah Carey's boobs."