'Manipulative' Britney Spears

Britney Spears is "manipulative and cunning", according to her father,

Dad Jamie - who is officially the conservator of Britney's financial affairs and estate - insists 26-year-old Britney has the ability to influence him, because she plays on their close relationship.

He told America's OK! Magazine: "She sometimes calls me 50 times a day and asks me things that light my life up. But, like all daughters, she is very manipulative and cunning. So she gets what she wants a lot."

Jamie also spoke about his feelings for Britney's ex-husband Kevin Federline, who was recently awarded full custody of his two sons, Sean Preston and Jayden James, with the pop superstar.

He said: "Kevin has a wonderful heart. He wants them to raise these kids together. Kevin's heart is right."

Jamie insists his relationship with Britney has improved considerably since he became her conservator.

He added: "We've grown a lot. I've been able to come back into my daughter's life, and that was an adjustment anyway, because I'm an alcoholic and it's the first time we've really been able to share."