Paramedics were called to the singer's Beverly Hills home at about midday on Thursday after he stopped breathing.
He was pronounced dead two hours later at the UCLA medical centre. Jackson's brother, Jermaine, said he was believed to have suffered a cardiac arrest.
He added: "The family request that the media please respect our privacy during this tough time."
"And Allah be with you Michael always. I love you."
TV footage showed the star's body flown from UCLA to the LA County Coroner's office where a post-mortem is expected to take place on Friday.
MICHAEL JACKSON
