Alexandra Burke threatens to sue mum?

Alexandra Burke has reportedly threatened to sue her mother after learning of her plans to release a tell-all book.

The News of the World claims that the X Factor winner called in lawyers from her record label Syco after learning about Melissa Burke's plans.

The book, titled Heart And Soul, allegedly features a picture of Alexandra on the cover and is due to be published in April.

"Alex couldn't understand why Melissa would want to write a book against her wishes," a source said. "She has a very dramatic past and doesn't want it all being dragged up again. So she begged her mum not to go ahead but Melissa needs the money.

"Everybody thinks she's rich because she's got this popstar daughter but the truth is she's an ill woman struggling to get by. Alex does her best to support her mum and would have kept doing that, but she said she'd have to get lawyers involved and sue if Melissa went ahead with her publishing deal."

Meanwhile, another insider claimed that Alexandra is worried that her mother's book will hinder her chances of writing an autobiography in the future.

"She had a very volatile relationship with her mum," the source added. "All she wants is Melissa to support her, not always try and be in the spotlight."

The mother and daughter previously clashed when Alexandra claimed in an interview that Melissa struggles to deal with her X Factor success.