Michael Jackson Estate Beefing With Auction House Over Unreleased Music for Sale

Michael Jackson's estate has issues with an auction house planning to sell his unreleased music to the highest bidder.

Gotta Have Rock and Roll is auctioning off some cassette tapes with never-before-heard MJ songs ... and the late singer's estate is blasting the sale as a "sad attempt by an auction site to mislead the public."

The auction item features two cassette tapes with 12 unreleased tracks Michael worked on in the late 1980s and early '90s ... before his "Dangerous" album. Gotta Have Rock and Roll is putting the tapes on the auction block with an $85,000 starting bid, and they expect the sale price to land between $150K and $200K.

Thing is ... Michael Jackson's estate tells us the cassettes are just copies of the original master recordings, which are owned by the estate -- and whoever buys the tapes will be unable to reproduce them or play them publicly because the estate owns the rights.

MJ's estate also took a shot at the formatting here ... calling cassette tapes "a long-outdated format." Oof. Millennials and Gen X, you're catching some strays.

Dylan Kosinski, president of Gotta Have Rock and Roll, is firing back ... telling us the cassettes are more valuable because they can't be reproduced or released to the public.

Kosinski says the fact MJ's estate is hoarding the master records in their vault only makes this auction a bigger deal.

Michael recorded the songs with music producer Bryan Loren ... and Bryan passed along copies to the consigner in this auction.