Mariah Carey and Nick Cannon
Mariah Carey's brother claims her marriage to Nick Cannon is a sham. (Getty)

Mariah Carey's brother has reportedly said he fears his sister could die like Whitney Houston.

According to the National Enquirer magazine, the singer's brother Morgan, who has not spoken with her in two years, has claimed Mariah has an alcohol addiction that he believes could kill her.

He alleges that the 45-year-old has been a heavy drinker since suffering from mental health problems in 2001, adding that he has never seen her sober. Morgan said: "Mariah was drinking through her pregnancy - even while she was nursing. I can't say that I have ever been around her when she was sober, and that's very scary."

He also alleges that Mariah takes a daily cocktail of medications including Zyprexa, Ativan and Depakote.

He said: "She does not have a support system, and she is not mentally capable."

Morgan adds that he believes the Hero singer is trying to numb her problems with wine and champagne following the breakdown of her relationship to husband to Nick Cannon. However, he claims that the marriage was a sham.

He describes Nick Cannon as a "crock of s**t" who was only interested in her money.

"Nick listened to people who said, 'Get with Mariah, she thinks you're cute, have kids and ride it to the bank.' Nick was there for the cash from day one. He doesn't give a damn about Mariah. Nick took tremendous advantage of her and continues to do so," he said.

Morgan is concerned the Without You singer has 'pushed away the only people who've been trustworthy' and will blame her entourage if anything does happen to her.

He said: "If my sister turns up dead ... I'm not going to look the other way! Anyone who's filling her glass is jeopardising her life!"

Mariah and Nick, who have two children together, confirmed their split in August 2014, after six years of marriage, revealing they had been living apart for months. Cannon, 34, is said to have filed for divorce in December of that year. But despite their differences, the former lovebirds are staying cordial for the sake of their three-year-old twins, Moroccan and Monroe.

Earlier in April, Cannon said "never say never" when asked by TMZ whether a reconciliation between the pair was on the cards.