Members of George Michael's family say they want a full investigation into how a 999 call made after his death was apparently leaked.
A statement issued by solicitors acting on their behalf said his loved ones are "truly appalled" that the audio recording was made public.
The former Wham! frontman's partner Fadi Fawaz said he found the star dead when he arrived to wake him at his home in Goring-on-Thames, Oxfordshire, ahead of a Christmas Day lunch.
The recording was said to have featured an excerpt of the conversation between Mr Fawaz and the emergency operation.
In a statement, the pop star's family said: "George's family and friends are extremely upset and truly appalled that such a personal, painful and clearly confidential recording has been leaked.
"On their behalf we will be ensuring that a full investigation takes place to establish how this material was made available and we will expect the culprit(s) to be dealt with appropriately."
It continued: "We firmly believe that anyone contacting the emergency authorities in situations such as this should be entitled to expect that recordings will not be released to the media and it is deeply distressing to the family that this transcript, and audio recording, has been made public."
Police said a post-mortem examination of the 53-year-old had proved "inconclusive" and the results of further tests are yet to be revealed.
Michael is set to be honoured at the Grammys with tribute segments during the ceremony, which will take place in Los Angeles on Sunday, although who will participate in them is being kept a secret.