New Jackson album: a thriller from beyond the grave?

Michael Jackson fans will this week finally get their hands on the pop icon's first record since he died, with huge sales expected despite lukewarm reviews and questions over its authenticity.

"Michael," due out Tuesday in the United States, comprises 10 songs the King of Pop was at various stages of completing when he died last year, and includes contributions from rapper 50 Cent, Lenny Kravitz and US singer Akon.

Two tracks have already been released online, the first of which - "Breaking News," a fierce protest at how the media hounded the scandal-tainted singer - sparked a fierce debate over whether it was really Jackson's voice.

Record company Sony - which plans to release a series of new Jackson albums - was forced to defend the album after fans and even some of Jackson's family members questioned the record's authenticity.

"We have complete confidence in the results of our extensive research as well as the accounts of those who were in the studio with Michael that the vocals on the new album are his own," it said in a statement.

Jackson's sister LaToya said bluntly that the record "doesn't sound like him." But more generally, purist Jackson fans question how some of the songs were completed, from material recorded sometimes several years ago.

At least one song, "Much Too Soon," was written at the time of Jackson's landmark 1982 album "Thriller," several stem from the time of his last album of new material, 2001's "Invincible."

The most recent track, "Band of Joy," stems from the months before Jackson's shock death in June, 2009 - he planned to keep working on it in London in between a series of sell-out concerts in July and August, producers say.

Jackson is credited as writer of all but two of the songs - "Another Day" by Lenny Kravitz and "Hold My Hand" by Akon, and producers are keen to stress how closely they kept to the singer's original intentions.

"While Michael was not there to complete the tracks as only he could, he had left behind a unique roadmap mapping out his creative vision in the form of notes and detailed conversations," they say in a 10-page media introduction, which spends two pages seeking to justify the album's authenticity.

Pre-release reviews of the new album - reportedly the first of a 10-album deal over seven years, although that is difficult to confirm - have been decidedly mixed.

"This is not a Michael Jackson album ... He would not have released anything like this compilation, a grab bag of outtakes and outlines assembled by Jackson's label," said Rolling Stone, although calling the album "compelling."

Entertainment Weekly gave it a "B" grade, saying: "As musical epitaphs go, Michael is a solid album, arguably stronger than Invincible and certainly no great affront to his name.

"But it can be hard to listen and not wonder what he would have done differently - or if he would have wanted us to hear it at all."

In Britain, music weekly NME's reviewer said the album was saved by the last two tracks: "Behind the Mask" which he describes as "brilliant" and the Thriller-era ballad "Much Too Soon."

"Oh, it isn't really very good, don't be under illusions of that. But compared with the unnecessary, inauthentic and insulting mess it could have been ... Michael' can actually be considered something of a win," he says.

But, perhaps inevitably, the album is already a bestseller with fans, much like last year's film "This is It," made from footage of rehearsals for the London shows.

The album - whose cover, in typical Jackson style, depicts him being crowned by cherubs with a biblical-looking star in the background - was number 11 in Amazon.com's top sellers this weekend, ahead of its actual release.