A post-mortem examination into the cause of George Michael's death was "inconclusive", police have revealed.
The singer died aged 53 on Christmas Day at his home in Goring-on-Thames, Oxfordshire.
His body was discovered in his bed by his partner, Fadi Fawaz.
Thames Valley Police said a post-mortem carried out on Thursday (29 December) had not been able to confirm the cause of death and that more tests were needed.
The police force said in a statement that results "are unlikely to be known for several weeks".
Officers said Michael's death is still being treated as "unexplained but not suspicious" and that a file is being prepared for the coroner.
Michael's manager, Michael Lippman, had said the singer died of heart failure, with his publicist adding there were "no suspicious circumstances surrounding his death".
Michael, who was born Georgios Kyriacos Panayiotou, sold more than 100 million albums throughout a career spanning over three decades.
His rise to stardom began as a singer in the 1980s duo Wham! with schoolfriend Andrew Ridgeley, before going on to launch a solo career.
Musicians from across the world have paid tribute to the star since his shock death, while fans gathered outside both his Oxfordshire home and his other residence in Highgate, north London.
Sir Elton John, a close friend of Michael, wrote on Instagram: "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 and all of his fans."
Sir Elton is expected to perform a special tribute at Michael's funeral, similar to the one he performed at Princess Diana's funeral in 1997.
Fawaz, a celebrity hairdresser who began dating Michael five years ago, described Michael as a "beautiful person", saying he will never forget discovering his body.
The pair had planned to go for Christmas lunch, with Fawaz turning up at Michael's home to get him out of bed.
"I went round there to wake him up and he was just gone, lying peacefully in bed," he told the Daily Telegraph. "We don't know what happened yet. Everything had been very complicated recently, but George was looking forward to Christmas, and so was I.
"Now everything is ruined. I want people to remember him the way he was – he was a beautiful person."
Michael had several plans for 2017, including a documentary about his life, entitled Freedom, due to be released in March.
Reports claim that the youngest of George's two elder sisters, Melanie, 55, is expected to inherit the majority of his £105m fortune.