NEW YORK (AFP) - Irish singer Sinead O'Connor vanished from Facebook on Thursday after a string of disturbing postings and her brief physical disappearance in the Chicago suburbs raised alarm.

The address for the singer's verified page said that the content was unavailable. It was unclear whether she left or was removed from Facebook, but the social media site last year temporarily deactivated her account after she suggested she had tried to overdose.

Fears for O'Connor's well-being returned this week when police in the Chicago suburb of Wilmette said that they were looking for her after she failed to return from a bicycle ride.

She was located a day later but soon returned to Facebook on which she castigated her former husband, John Reynolds.

"Every one of you had better pray I die," she wrote.

She confirmed mental health problems and accused her family of not understanding her, saying they "brutalized" her and led her to flee to the United States.

"Such is the fate of Irish people with mental illness," she wrote.

O'Connor has won critical acclaim for her haunting voice and style, especially on her first two albums, The Lion And The Cobra and I Do Not Want What I Haven't Got.

She is best known for Nothing Compares 2 U, a ballad written by pop legend Prince, who died last month.

But O'Connor has also been a consistently controversial figure. The singer, who says she was abused by her mother, is a vociferous critic of the Roman Catholic Church for not doing more to protect children.