British pop singer George Michael has died, the British news agency PA reported Sunday, citing his publicist.
"It is with great sadness that we can confirm our beloved son, brother and friend George passed away peacefully at home over the Christmas period," PA quoted the star's publicist as saying.
"The family would ask that their privacy be respected at this difficult and emotional time," the agency quoted the publicist as saying. "There will be no further comment at this stage."
Michael's death was being treated as "unexplained but not suspicious," the Thames Valley Police said.
Friends and colleagues reacted with incredulity and sadness on Twitter.
Singer Elton John posted a photo of himself with Michael on Instagram with the caption: "I am in deep shock. I have lost a beloved friend - the kindest, most generous soul and a brilliant artist. My heart goes out to his family, friends and all of his fans."
Madonna posted: "Farewell My Friend! Another Great Artist leaves us. Can 2016 Fuck Off NOW?"
Singer Bryan Adams tweeted: "RIP George Michael. I can't believe it. Such an incredible singer and a lovely human being, far too young to leave us."
Talkshow host Ellen DeGeneres said, "I just heard about my friend @GeorgeMichael's death. He was such a brilliant talent. I'm so sad."
The 53-year-old Michael rose to fame as a member of pop duo Wham! with Andrew Ridgeley, known for their hits "Club Tropicana" and "Last Christmas."
The son of a Greek Cypriot father and British mother, his real name was Georgios Kyriacos Panayiotou. He went on to have a successful solo career after Wham! split up in 1986.
The artist, who was initially reticent about his private life, came out as gay after a very public arrest for a "lewd act" in a Beverly Hills restroom in 1998.
He responded with a tongue-in-cheek song, "Outside," with a video featuring policemen and a row of gleaming urinals in an apparent reference to his arrest.
Michael sold more than 100 million albums throughout his career spanning almost four decades.
"Outside" (1998), "Faith" (1987) and "Careless Whisper" (1984) were among his biggest hits as a solo artist.
The death of his mother and of his life partner plunged Michael into depression and crisis in the 1990s.
The artist had a difficult relationship with fame and fortune and had several run-ins with the law relating to drug offences. He pleaded guilty to charges of driving while unfit through drugs in 2007 and 2010.
Michael suffered a bout of pneumonia and spent four weeks in hospital in Vienna in 2011.