The pop singer described BBC director general Mark Thompson's announcement that 6 Music and Asian Network are facing closure at the end of 2011 as "bad news" for British music.
"It will be awful if they do decide to close BBC 6 Music, and I hope that the backlash they've received so far will make them think twice," she wrote.
"Clearly it will continue to cause an uproar, which is the last thing the BBC want. Perhaps they weren't expecting this level of interest in a niche station.
"I read that they want to invest in quality over quantity, but how does that make sense? If they close 6 Music, instead of acts like Seasick Steve and presenters like Lauren Laverne, it will be the Pussycat Dolls and Fearne Cotton on Radio 1."
She added: "The only way this decision will be palatable is if they incorporate the elements of BBC 6 Music that strike a chord with the public into one of their other channels, such as Radio 2.
"That would mean making a commitment to showcasing new and unsigned bands, not just bands on major labels, and giving space to bands who haven't got a platform anywhere else, not just the next hyped act. But honestly I don't feel very hopeful that this will happen."
> Musicians, DJs call for 6 Music reprieve