Sir Elton John has admitted "I don't know how much time I have left".

The 77-year-old musician spoke about life and death in his upcoming documentary 'Elton John: Never Too Late' and revealed he thinks about his own mortality now more than ever.

According to The Mirror, in one scene from the doc, Elton says: "I wonder what is going to happen to all of my stuff when I finish? This is the latter time of my life. I don't know how much time I have left.

"You think about that more when you get to my age. You think about life and death. You think, 'Well I just want to be where I want to be now'.

"I don't have to work after this. I will work and do records and putting radio shows together but travelling does take so much out of you.

"It is very tiring. I am used to it. I am a veteran at it but this is where you start to think about mortality."

The new Disney+ documentary is a look back at Elton's career in the entertainment industry and contains never-before-seen footage of his handwritten diaries, audio tapes from some famous interviews and John Lennon joining him on stage for Thanksgiving 1974 in Madison Square Garden.

Elton and his husband David Furnish, 61, have sons Zachary, 13 and Elijah, 11, together and Elton admitted the boys also think about his mortality.

He said: "They worry as they know how old I am. Not so much David but me. They love their Daddy so they want me to be around forever.

"I want to be around forever. I want to see them have children, get married, but I don't think I am going to be around for that. Who knows? You never know.

"So that is why I want to make the best of my time while I am around. Our time together is so wonderful and precious."