The music legend was found dead at his Oxfordshire home on Christmas Day and his autopsy later reportedly remained "inconclusive", causing an initial delay.
Police are said to have warned that it could be "several weeks" until the late 53-year-old's body is released.
His loved ones are believed to be finding the delay "intolerable" and his father is even struggling to leave his home.
Greek radio host Vasilis Panayi told the Daily Mirror: "It’s very hard for all of them, quite intolerable.
George Michael's funeral might not be held until next month, according to reports
George Michael's family launch full investigation into leaked 999 call
Grammys 2017: Adele SWEARS and RESTARTS George Michael tribute
George Michael was found dead on Christmas Day
George Michael's boyfriend has reportedly been banned from the funeral
George Michael in pictures
Mon, December 26, 2016
Pop icon George Michael in pictures
1 of 16
Get Quotes on Home Insurance
George Michael Performs At Palais Garnier in 2012
George Michael's family are finding the wait intolerable.
"It’s a shock and terrible for his father. He was looking forward to a happy old age and now all he has is grief."
He continued: "He wants to hold the funeral but so far the police are refusing to release the body and are looking for further clues."
Meanwhile, family friend Demetri Louca, added: "George’s body is still with the coroner in Oxfordshire. His family are finding the wait intolerable.
"His body will be there until they have found the cause of death and apparently it is very nearly finished now. They are planning the funeral with the high priest and will announce the date in time."
George Michael's autopsy reportedly came back inconclusive
Cheryl remembers her close friendship with George Michael
Fadi Fawaz pays tribute to boyfriend George Michael
Dramatic moment Fadi Fawaz tells 999 caller George Michael is dead
George Michael: Adele paid tribute to him at the Grammy's last night
The singer's lover Fadi Fawaz has been "banned" from his funeral, according to claims made by his close childhood friend.
The news comes after Adele halted her tribute to George at the 59th Grammy Awards last night.
"I’m sorry for swearing and I’m sorry for starting again. Can we please start it again? I’m sorry, I can’t mess this up for him," the 28-year-old told the star-studded crowd.