'Michael', released this week, features collaborations with Akon and 50 Cent, and was completed after his death last year.

It also includes the late singer's duet with Akon, entitled 'Hold My Hand', which originally leaked online in 2008.

In an interview with Rolling Stone, Will.i.am said Jackson would never have allowed an album to be released without his involvement.

He also revealed that the star called him to express his sadness when 'Hold My Hand' leaked.

"A couple of months before Michael died, he called me on the phone really upset. 'Hey, it's Michael,' " the singer said.

“'Somebody leaked one of these songs. Why would they do that? Who does that?' I said, 'What song, Mike?' 'Some song called 'Hold My Hand.' I swear to God I had this conversation with him."

He added: "I knew this man, and he was very critical about every single detail. He stood in the studio himself, mastering and mixing everything. How can you release a record without that Michael Jackson? It's not Michael Jackson.”

Critics have slammed the release, while fans have remained divided over the effort.

Jackson died last year at his home in Los Angeles at the age of 50.

(by Jason Gregory)