Susan Boyle could be withdrawn from the final of Britain's Got Talent amid fears for her mental health, it's been reported.

The 47-year-old, who has become an overnight singing sensation, is said to be acting increasingly erratically.

Earlier this week, Susan was pictured losing her temper with a police officer, and she even threatened to quit the show on Wednesday, according to The Sun newspaper.

"The last thing producers want is a meltdown on national TV,” a source said. “It's been made clear that if she's not right mentally, she won't appear in the final."

Susan, who has learning difficulties, shot to fame in April after her audition on the talent show. A video clip of her performance has been watched over 100million times on YouTube.

But Britain's Got Talent bosses are understood to be growing concerned with how the singer is dealing with her moment in the spotlight.

The star has already been moved from her West London hotel to a secret location.

Yesterday, judge Piers Morgan revealed Susan had been finding it “very difficult to cope” with the pressure of performing.

“She has been in tears many times during the last few days, and even felt like quitting altogether and fleeing all the attention,”he added.

Susan is the red hot favourite to win tomorrow's final, which will see ten contestants battle it out to win the chance to perform at the Royal Variety Performance later this year.

Britain's Got Talent's Susan Boyle