Unheard Joy Division outtakes are among a stash of rare tapes to have surfaced, according to a former studio engineer who says she rescued them from a skip.
Julia Adamson worked at Stockport's Strawberry Studios and says she saved tapes by bands including Joy Division and Magazine when it shut 20 years ago.
She revealed the details on Facebook, saying she no longer wanted the tapes.
One recording features outtakes from Joy Division's 1979 sessions for the Unknown Pleasures album, she said.
Ms Adamson, who is also a former member of The Fall, said she salvaged the tapes when the studio's entire archive was binned after its closure in the early 1990s.
"They were just throwing everything in skips," she told BBC News. "They were throwing it all out and we were a bit devastated."
She and her husband, fellow engineer Chris Nagle, rescued recordings produced by Martin Hannett, who worked with Joy Division among other seminal Manchester bands, plus "anything else we thought we should hang on to", she said.
"We didn't see it as valuable, we just didn't like the idea of them being thrown in a skip," she said.
In the Facebook thread, she said she wanted them to go to a collector as she did not want to look after them any more.
She posted a photo showing almost 30 tape boxes with hand-written titles bearing the names of bands including New Order, The Durutti Column, Magazine and The Psychedelic Furs.
Many are copies of master tapes, with the originals still in existence elsewhere, she said.
But one, titled "Joy Division outtakes", features recordings of the songs She's Lost Control, Wilderness and New Dawn Fades that "haven't been heard before as far as I'm aware", she said.
"They're quite different to the album," she said. "They're earlier versions before they did the final take, but they are really good."
Joy Division were one of the most influential bands of the 1970s. After singer Ian Curtis killed himself in 1980, the remaining band members went on to find further success as New Order.
Julia Adamson now runs the Manchester-based record label Invisible Girl.