A cassette tape containing unreleased early tracks by Prince is set for auction.

The songs, recorded in the 1970s, feature alongside three early versions of tunes he would later release, including So Blue, Gotta Broken Heart Again, and Sometimes It Snows in April.

According to TheWrap, two of the unreleased tracks feature “bouncy, upbeat choruses and risque lyrics”, while the third song comes with “a chorus that includes very candid sexual pleas from Prince.”

The iconic musician’s guitarist and frequent collaborator Dez Dickerson is putting the item up for sale, and writes: “Prince originally gave me the cassette in late 1978 because he wanted me to listen to a record he had recorded on side A (a female-fronted funk band whose name I don’t remember now).

“Sometime during the next year or so, I used the A side to record some scratch bass and guitar parts for songs I was going to be recording for a rock/power pop demo I was doing, recording over the original content (you can still hear a snippet of the funk record at the end of the side).”

While the minimum bid on the cassette tape is $20,000 (£12,500), it’s not the most expensive item up for grabs in the upcoming Prince auction – that title belongs to the diamond engagement ring he presented to ex-wife Mayte Garcia.

The stunning bauble and five handwritten “heart notes” Prince used during the romantic proposal will start at $100,000 (£62,500).

Prince and Garcia wed in 1996, but divorced three years later.

Other items up for auction include a 1959 acoustic guitar the singer used to record his early demos, various outfits he has worn over the years and fine china used at his wedding, but it is unclear whether the plates were used at the ceremony with Garcia or his second wife Manuela Testolini.

Prince and Testolini split in 2006, after five years of marriage.