The Sunday Mirror reports that the soul singer, who left the house abruptly following an altercation with Perez Hilton, stayed in a London hotel where he sought drugs from a dealer twice in 14 hours.
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Alexander O'Neal was popular with the other CBB housemates, but decided to leave early
However, he has now vowed to seek help for his issues, with his spokesperson claiming it was a momentary relapse for the singer, who has had treatment in the past for addictions, and will be doing so again.
His spokesman added, “It has been extensively reported how this series of CBB has been one of the most stressful and volatile in the history of the show.
“Alexander has a lot of positive projects to look forward to over the next few months, including a tour and new material he is working on, and hopes this momentary lapse will not interfere with those.
“He asks his fans to forgive him and apologises if he has let any of you down.”
CBB viewers saw O'Neal get wound up by gossip blogger Perez Hilton and calling him a "f*****"". He later apologised, but chose to leave the show, much to the distress of the other housemates, who had supported "the big man".
During his time on the show, Alexander had discussed his addictions with recovering alcoholic Keith Chegwin, telling him, "I’ve been in several treatments for drugs. Cocaine.
“The counsellor was saying, ‘You’re never going to get off the drugs unless you get that chip off your shoulder’.”
Alexander's popularity has soared since going into the CBB house, and he has a string of gigs lined up in the UK. He has also been in the recording studio with Basement Jaxx, and discussed doing music together with model Katie Price while he was in the house.
The show's finale on Friday evening saw Katie Price crowned this year's winner, with runner-up Katie Hopkins followed by Calum Best in third place.
10 Stars You Forgot Did 'Celebrity Big Brother'
Mark Owen(01 of10)
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Mark even appeared to have forgotten that he'd done 'CBB' himself, when - shortly after Take That's comeback - they said they were pleased none of them had done reality telly in their break.So that wasn't you winning 'Celebrity Big Brother' in 2002, then, Mark? (credit:Rex/Philip Toscano)
Germaine Greer(02 of10)
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Feminist commentator Germaine Greer lasted just five days in the 'CBB' house before walking, following the arrival of her housemate, Brigitte Nielsen's mother in law, Jackie Stallone.Why anyone would pass up the opportunity to spend any time with Jackie is beyond us, but we're sure Germaine had her reasons. (credit:Rex)
H from Steps(03 of10)
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He may be a big character, but H's stint in the house in 2007 was somewhat overshadowed by the racism controversy that surrounded the series that year.Apparently, being a 'Celebrity Big Brother' housemate also made H forget how to do his shirt up properly too. (credit:Rex/David Fisher)
Tommy Sheridan(04 of10)
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Everyone remembers George Galloway's appearance on 'CBB' - largely thanks to one spandex suit, and one unforgettable cat impression - but he isn't the only Scottish politician to have been in the house. (credit:Rex)
Sue Perkins(05 of10)
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She may be now known as a co-presenter on the 'Great British Bake Off', but one of Sue's lesser known accolades is her stint in the 'CBB' house back in 2002, when apparently camouflage-print cargo trousers were all the rage... (credit:Andy Butterton/PA Archive)
Martin Kemp(06 of10)
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He started off the series as the favourite to win, but ultimately the former 'EastEnders' actor and Spandau Ballet guitarist's time in the 'CBB' house was surprisingly uneventful, and he finished in third place behind Colleen Nolan and Julian Clary. (credit:Ian West/PA Archive)
Vinnie Jones(07 of10)
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Hardman actor and ex-footballer Vinnie Jones spent four weeks shacked up in the 'Celebrity Big Brother' house with Stephanie Beacham, 'The Thong Song' singer Sisqo and Alex Reid - a far cry from his A-list life on set with Ian McKellen, Brad Pitt and Halle Berry. (credit:Rex/Channel 4)
Ivana Trump(08 of10)
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The highlight of Ivana's time in the house was when she'd been convinced as part of a task that she'd won a sought-after European award, only for her housemates to drink water out of it and, eventually, smash it. She also donned some questionable flesh-coloured underwear as part of a life drawing task. (credit:Rex/Channel 4)
David McIntosh(09 of10)
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David didn't have much time to make an impression on viewers during his short-lived time in 'CBB' last summer - he only managed to last 10 days before being given the boot. (credit:Karwai Tang via Getty Images)
Jack Dee(10 of10)
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He might prefer not to mention it now, but Jack Dee was the first ever winner of 'Celebrity Big Brother' back in 2001. The whole series might have only lasted eight days - a walk in the park compared to latter day runs - but even that was too much for Jack, who at one point famously tried to tunnel his way out of the house. (credit:Rex/Julian Makey)