Her close friend Dave Baker told the publication that Alison was suffering from a “problem with her internal organs”.

Baker also paid tribute to his friend, adding: “Beneath a tough exterior, Alison was a highly intelligent, warm and sensitive person.

“I have known her for nine years and as her friend and in recent months as her caregiver. I will miss her dearly. Farewell Alison. May you now find peace, your tormented soul forever free from earthly pain.”

Carey reportedly had a complicated relationship with her 63-year-old sister, as her estranged brother was homeless and struggled with personal issues throughout his life.

Carey wrote in her memoir The Meaning of Mariah Carey that it was “emotionally and physically safer for me to not have contact” with Alison and her brother Morgan.

Obsessed singer Carey has previously revealed that she also had a strained relationship with her mother.

The Mirror reported in her autobiography: ‘Like many aspects of my life, my journey with my mother was full of contradictions and competing realities.

“It’s never just been black and white – it’s been a whole rainbow of emotions. Our relationship is a prickly rope of pride, hurt, shame, gratitude, jealousy, admiration and disappointment.”