Before her tragic death in July 2011, Amy Winehouse apparently recorded demo versions of tracks intended for a third album – however, they’ll never see the light of day because they were destroyed by her record label Universal.

David Joseph, the chairman / CEO of the major label, told Billboard that the decision was taken to stop unauthorised sampling in the future. “It was a moral thing,” he said, “taking a stem or a vocal is not something that would ever happen on my watch. It now can't happen on anyone else's.”

The revelation came as part of an extended feature article, in a series of interviews with the late singer’s friends, fans and collaborators, ahead of the theatrical release of documentary movie Amy.

Amy WinehouseAmy Winehouse demos were destroyed by her record label

Other revelations in the article include the origins of several of her hit songs from Back To Black, the inspiration she had on the likes of Sam Smith, and plans that Winehouse had mooted for a jazz / hip-hop collaboration with The Roots’ drummer Questlove.

More: Amy Winehouse documentary ‘In Her Own Words’ debut on BBC iPlayer

Meanwhile, the makers of Amy, which is released on July 3rd, have revealed that they’ve discovered another trove of unreleased music made by Winehouse. The material is believed to be completely different to the Mark Ronson-curated collection Lioness: Hidden Treasures released the same year as her death, and to the demos referred to above.

Director Asif Kapadia, producer James Gay-Rees and editor Chris King came upon the recordings during the two year process of making the film, and are campaigning for them to be released by Universal.

King said: “I would recommend they find a way to release some of the stuff we listened to. There's one recording where she's getting back with Blake Fielder-Civil: it's just piano and her singing, which is such a massive emotive performance. There are songs like that and cover versions we couldn't work into the film that I'd love everybody to hear.”

More: ‘Amy’ documentary wows critics but angers Winehouse family at Cannes premiere