An epic Beatles improvisation could be released 41 years after it was recorded, Sir Paul McCartney has revealed.
The 14-minute track called Carnival of Light - a jumble of shrieks and psychedelic effects - was never released because three of the Fab Four thought it too adventurous.
"It does exist," McCartney told a British radio arts programme to be broadcast this week.
The former Beatle confirmed he still had a master tape of the work and said he thought "the time has come for it to get its moment".
Recorded in 1967 by McCartney, Ringo Starr, George Harrison and John Lennon at London's Abbey Road studios, Carnival of Light was played just once in public - at a music festival the same year.
It features the sound of gargled water, church organs and distorted guitar riffs along with Lennon and McCartney shouting random phrases such as "Are you all right?" and "Barcelona!".
McCartney said he suggested recording the track after being commissioned to create a piece for the festival.
The other three Beatles reportedly regarded it as too odd to release.