Legendary rock group Led Zeppelin have unveiled two previously unheard recordings ahead of the reissue of the band's first three albums in June.
The two tracks - blues classic "Keys to the Highway", recorded in 1970, and an early version of the famous song "Whole Lotta Love" - are among dozens of tracks which the band will officially release alongside the reissues.
The companion discs will feature alternative versions of songs, works in progress and live performances, all recorded at the time of the original albums.
The tracks, like hundreds of others, had been carefully catalogued but then locked away in the the band's archive for decades.
Guitarist Jimmy Page, 70, has spent two-and-a-half years combing through the vaults, listening to hundreds of quarter-inch tapes before choosing the best material.
"I don't want to die and have somebody else do it" he says. "I'm authoritative about what was done in the first place."
Page says the new material "deserves to be heard" because "it's performance art".
It will give fans the first chance to eavesdrop on some of the band's key recording sessions.
Keys to the Highway/Trouble in Mind, to appear on Led Zeppelin III, was recorded in 1970 at the Olympic Studios in Barnes in south-west London, about half an hour after Hats Off to (Roy) Harper. But it was never released.
"It was a particularly prolific time" says singer Robert Plant, "where we were learning about each other's capabilities.
"Jimmy and I were just fooling around with the stuff that we would play at home. We were just trying things out. Nothing was premeditated."
You can listen to the songs here.