"He had every opportunity to stop what was happening to her — her descent into prescription pill addiction — but he didn't. I believe 100 per cent he was an enabler."
Phillip – who was introduced to Spears in 2003 and became her personal trainer in 2006 – also blamed Jamie for the Toxic hitmaker's infamous 2008 breakdown, as he said his "controlling" nature pushed Spears over the edge.
Spears was placed under conservatorship just days after her breakdown, which gave her father control of her estate and all aspects of her career and life.
Phillip added: "Britney was just so sweet, kind, loving and fun — and also so much smarter than people gave her credit for.
"Her meltdown wasn't because she was crazy. It was because what was happening to her was driving her mad. Jamie was known as a raging alcoholic.
"He seemed largely indifferent about his daughter.
"Management wanted to control and manipulate the energy around her. They just wanted to milk their cash cow."
And Phillip said he's "really proud" of Spears' fans for kickstarting the "Free Britney" hashtag, which helped bring awareness to the star's situation.
He told the Sun newspaper: "I'm happy for her that she is moving forward in the right direction, because I've seen too many other people die.
"I'm also really proud of her fans for actually moving this forward, because they really have done a lot to get it to where it is today.
"I do think that at some point Britney did need guidance, but the conservatorship is ridiculous. It's simply a money grab."
