NEW YORK (NYTimes) - As the first anniversary of Prince's unexpected death approaches, a lawsuit filed on Tuesday (April 18) by his estate aims to block the release of a new six-song EP credited to the singer.

The previously unreleased Prince music, finished and packaged by audio engineer George Ian Boxill, a former collaborator, is scheduled to come out digitally on Friday, exactly one year after Prince's death, with physical copies due in stores on June 2, according to an announcement on Tuesday. The tracks, called the Deliverance EP, were recorded between 2006 and 2008; one song, Deliverance, is currently available for sale and streaming via iTunes and Apple Music. (The full EP was also made available early as a download, for US$6.99 or US$19.99 depending on audio quality, at princerogersnelson.com.)

"The songs were written and recorded when Prince was an independent artist, protesting what he saw as an unjust music industry," the announcement said. "In the spirit of that independence, and in supporting Prince's opinion of major label contracts, Deliverance is being released independently via RMA, a Vancouver, WA, based record company. The majority of all sales of Deliverance will benefit Prince's estate."

But in a federal lawsuit filed on Tuesday, the Prince estate, which is now being managed by Comerica Bank & Trust and Paisley Park Enterprises, claims that Boxill has no legal right to release the music and is violating the terms of his agreement with Prince "for his personal gain at expense of the Prince Estate".

In February, the estate announced that it had made an agreement with the Universal Music Group for a large portion of his recording catalog, including albums made after 1995 as well as unreleased material in Prince's storied "vault" from throughout his career. But the status of that deal, which may be worth US$30 million or more, was cast into doubt this month, adding further confusion to the estate's management.

Universal complained to the estate that the company had been misled in negotiations, and that it learned only after the deal was completed that some of the rights it had paid for conflict with others secured by Warner Music, which controls most of the releases from the first half of Prince's career. Universal is considering legal action to cancel the deal and recover its payments, according to a person with knowledge of the company's plans, who was not authorised to discuss them.

The judge in the case alluded to turbulence in a filing last week, stating that the court has "learned that litigation might be forthcoming" relating to the estate's special administrator, Bremer Trust, a Minnesota bank that oversaw the estate until it was replaced in February by Comerica.

The planned release of Deliverance by an outside party is another wrinkle in what has proved to be an estate situation complicated by the fact that Prince died without a will.

According to the lawsuit, Boxill signed a confidentiality agreement with the singer that said the pair's recordings "would remain Prince's sole and exclusive property", that the engineer "would not use any recordings or property in any way whatsoever" and that "he would return any such recordings or property to Prince immediately upon request". The agreement also stated that Boxill had "no right to give interviews or write books, articles, etc." about the singer, court papers said. (The lawsuit was initially filed in district court last week in Carver County, Minnesota, where Prince was based, but was then refiled in federal court.)

In the album announcement, Boxill, who has also worked with Janet Jackson and Tupac, was credited as a writer and a producer of the tracks.

"Prince once told me that he would go to bed every night thinking of ways to bypass major labels and get his music directly to the public," Boxill said in a statement. "When considering how to release this important work, we decided to go independent because that's what Prince would have wanted." Boxill and RMA (Rogue Music Alliance), the label behind the release, did not immediately respond to a request for comment about the lawsuit.

The estate is seeking a permanent injunction against the release, the return of the master recordings and civil liability for theft.