Mariah Carey's older sister is suing the US singer for $1.2m (£875,000) for "immense emotional distress" she says was caused by remarks in her memoir.

In her complaint, Alison Carey referred to claims in the book that she gave 12-year-old Mariah Valium, tried to pimp her out and threw boiling tea on her.

Alison denied the claims, saying Mariah "presented no evidence to substantiate these serious allegations".

The pop star published The Meaning of Mariah Carey in September.

Alison, who was 20 at the time the alleged events took place, filed her two-page legal complaint at New York Supreme Court on Monday.

It said the "outrageous" material in Mariah's book was meant to "humiliate and embarrass" her sister.

Mariah used "her status as a public figure to attack her penniless sister, generating sensational headlines describing her lurid claims to promote sales of her book", Alison claimed.

She is now seeking damages for the "heartless, vicious, vindictive, despicable and totally unnecessary public humiliation".

She also said she was severely depressed due to the "unspeakable trauma of her childhood and having her own children abandon her". According to the document, Mariah had publicly acknowledged her sister, or "ex-sister", to be a "deeply wounded" person.

The BBC has asked the singer's representatives for a comment.

Alison dropped in and out of Mariah life, through teenage pregnancy, drug dependency and suicidal thoughts, the performer wrote. Although they shared some tender moments, the singer depicted several occasions when she believes Alison put her at risk.

One story involved her sister's boyfriend, who - Carey says she later realised - was running a prostitution ring. Aged 12, she claimed she was tricked into spending a night alone with him, ending up at a card game and a drive-in movie, where "almost immediately" he put his arm around her.

Immobilised and terrified by the "handgun resting against his thigh", Carey said she only escaped after another car pulled up alongside them, prompting John to leave and drive home "in silence".

The singer believes she was at risk of being pimped, reasoning: "Dysfunctional families are ideal prey for abusers, the exposed little ones vulnerable to being picked off."

Speaking to The Sun when the book was published, Alison denied the claims and said she was shocked and appalled that Mariah would accuse her of pimping her out.