Bruce Willis and Demi Moore's youngest daughter allegedly checked into rehab last month

A source told Star magazine that the 20-year-old blogger, whose mother sought help for "stress and exhaustion" in 2012 after splitting from her third husband, Ashton Kutcher, and for drug and alcohol abuse in the 1980s, secretly began treatment at the famous facility after Demi convinced her to seek help.

According to the magazine, Bruce threatened to cut Tallulah off financially in May after his 23-year-old daughter, Scout, informed him she saw Tallulah using drugs at a party.

But she decided to move to New York City in mid-June instead, where her problems are said to have spiralled out of control until her mother intervened.

The insider added: "Demi had been shocked when Tallulah confessed to her. But she knew enough not to judge. She knew her daughter needed her and she was glad she could be there to help."

A spokesperson for Tallulah, who was arrested when she was 17 for underage drinking, declined to comment to the MailOnline "at this stage."

The blonde beauty recently revealed she always felt "ugly" and was diagnosed with body dysmorphia when she was 13.

She said: "I was trapped in this body. I started starving myself and losing a bunch of weight and I got down to like 95 pounds. When I lost my curves and when my boobs shrivelled up into like nothing and I had no shape. It put me in even more of a cage."

Demi and Bruce, who also have daughter, Rumer, 25, split in 1998 after 11 years of marriage.

The 'Die Hard' actor also has daughters Mabel, two, and Evelyn, three months, with wife Emma Heming.