Spears scrawled 666 across her bald head claims News of the World.[AFP]

The News of the World reports an unnamed friend as saying "Last Saturday she said she had the number 666 written onto her bald head. She was crying, and shouting, 'I am the Antichrist!'

"The clinic people just didn't know what to do. Then she started screaming, 'I'm a fake! I'm a fake!' It must have been really frightening.

"When she tried to hang herself it was more a cry for help," the source said.

The paper also quotes another "pal" as saying her recent bizarre behaviour has been caused by use of crystal methamphetamine, a drug that can induce delusions and paranoia.

It claims the pop star had earlier threatened to overdose on paracetamol if her estranged husband Kevin Federline was granted custody of their two children.

"Britney held up two bottles of Tylenol and shouted, 'I'm gonna do this, this is it! I'm through with the whole f***ing circus'."

Ironically, it is Federline who is credited with helping the star through her difficult time.

"Kevin has been a real tower of strength for her and she has finally decided to give their marriage another shot," said a source "close to Britney".

"She thought things were over between her and Kevin after his wild partying and gambling.

"She felt he had deserted her and left her to bring up their two children on her own.

"She never even dreamed she would take him back.

"But Kevin's like a different man now. He's never been so caring before, and is really worried about Britney.

"He's been Britney's rock during her difficult time, and she wants to give him another chance.

"This week she even asked if she could have a night away from the Promises Clinic with Kevin. She's still waiting to hear if they will give her a pass so that they can go out for a romantic meal together.

"Kevin has also taken their two little boys to see their mum in rehab."