Minneapolis - Prince's estate is claiming a sound engineer who worked with the musician on five tracks in 2006 is threatening to release the unpublished material and has no right to do so.
The estate and Paisley Park Enterprises have sued George Ian Boxill, alleging he's trying to exploit the songs for personal gain. They say Boxill has no right to the recordings, and they're demanding he return them.
Attorneys for Boxill didn't immediately respond to a request for comment.
The lawsuit says a 2004 confidentiality agreement shows Boxill agreed that all recordings would remain Prince's sole and exclusive property. Prince sings and plays guitar and keyboard on the tracks. Court documents say the recordings, including one called Deliverance, are worth more than $75 000.
Prince died on 21 April of a drug overdose.