Former X Factor contestant Chico Slimani has suffered a stroke.
The 47-year-old, who was a popular star on the second series of the show, fell ill on the way back from performing a gig at the weekend.
A statement from his publicist said he was undergoing further tests and asked for privacy for his family.
He reached the quarter-finals of the 2005 series and had a number one in 2006 with It's Chico Time. He also took part in Dancing on Ice in 2012.
He appeared in the Christmas special of Ricky Gervais's BBC One sitcom Extras in 2007, and also released a fitness DVD.
His publicist Kym Rowlingson said: "This has been a great shock to Chico, his wife and their two children, also his close friends and family.
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"We thank you in advance for giving Chico and the family some privacy at this time."
Speaking in 2013 to mark 10 years of the X Factor Chico told the BBC: "Being on the show meant absolutely everything to me. It changed my life and my family's".
He said he had made a good career and living out of "being a novelty act".