NEW YORK, Oct 12, 2009 (AFP) - A previously unreleased song by Michael Jackson entitled "This Is It" was unveiled to the world on Monday almost four months after the star's death.

The track was released at the stroke of midnight at www.MichaelJackson.com, marking "yet another exciting moment in music history for one of the world's most revered artists," Sony Music Entertainment said in a statement.

The recording features backing vocals by Michael's brothers and will be played during the closing sequence of the forthcoming film "Michael Jackson's This Is It" and feature on a two-disc CD set of the same name.

A new photo of Jackson taken during rehearsals at the Staples Center in Los Angeles will also be unveiled, the record label said.

The album will go on sale later this month to coincide with the worldwide release of the movie on October 28.

Disc one of the album features some of Jackson's biggest hits such as "Billie Jean," "Smooth Criminal," "Human Nature," and "Thriller" arranged in the same sequence as they appear in the film.

The disc ends with two versions of "This Is It," the original and an orchestral one.

Disc two offers fans the early demo versions of classics "She's Out Of My Life," "Wanna Be Startin' Somethin'," and "Beat It" It also features a recently discovered spoken word poem by Jackson entitled "Planet Earth".

The film will offers a behind-the-scenes look at the performer as he rehearsed for his sold-out concerts that would have taken place this year in London, Sony said.

Chronicling the months from March through June 2009, the film is drawn from more than one hundred hours of behind-the-scenes footage, featuring Jackson rehearsing a number of his songs for the show.

Jackson died on June 25 at age 50 after taking a lethal cocktail of prescription drugs. The coroner's office has ruled his death a homicide.