Speaking in an interview to be broadcast on Friday's Top of the Pops, the band finally admitted that she had quit.
Solo career for Kym?
Band member Danny said: "We can confirm that Kym has left the band," but added: "Hear'Say will go on."
Kym is also expected to carry on in showbusiness, but as a solo artist.
Myleene, with whom Kym is said to have rowed, said: "like any other band there were arguments, that's what happens."
Hear'Say were created by the television programme Popstars last year, and have released two albums and had two number one singles.
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