Chicago (AFP) - Officers were on the lookout on Thursday (June 23) for Irish singer Sinead O'Connor, after receiving a tip that she may be in a suicidal state, the Chicago Police Department said.

The department said it had sent an "advisory message" to its units to be on the lookout for the musician, although it was not actively searching for her.

According to the American media, a Dublin police sergeant contacted Chicago earlier in the day to warn that O'Connor had made life-threatening statements about jumping off a Chicago bridge.

The 49-year-old singer created a stir last month when she failed to return from a bicycle ride, but was ultimately found safe in the Chicago suburbs one day later.

O'Connor, who has always been known for her strong views, has recently posted a string of messages on Facebook that have raised alarm.

Late last year, she suggested she had tried to kill herself with an overdose.

Then following her May disappearance, her page vanished from the site after a series of disturbing posts, including one that read: "Every one of you had better pray I die."

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 in April.