Writing on Twitter, the former Sugababes star told followers that 'Gimme Pressure' will not appear on her forthcoming debut solo album.
The track appears to be about the singer's final days with the girl group before she was ousted and replaced by Jade Ewen.
"Im disappointed that a track written almost 2 years ago when i was going through a difficult time(which you all know about) has been leaked (sic)" Buchanan wrote. "With the support of my wonderful fans im now in a great place. My album is very positive, that song will not be on it."
She added: "Cant wait for you all to hear the album."