Los Angeles  - Michael Jackson's first single to be released since his June death descended into fiasco Tuesday as it emerged that the track had been released in
1991 by an obscure Latin singer.

The singer's estate also admitted that the track had been written and recorded in 1983 together by Jackson and singer and song writer Paul Anka, and agreed to give the crooner 50 per cent of the copyright.

"They realize it's a mistake, they realize it's my song, they realize it's my production of his vocal in my studio and I am getting 50 per cent of the whole project, actually, which is fair," said Anka in a video statement on the celebrity website TMZ. com gossip Web site.

Anka, 68, said that Jackson took the tapes from his studio after the pair had a falling out in 1983, and their recording was never released. It was originally titled I Never Heard and both he and Jackson were credited as co-authors on its 1991 release by Puerto Rican singer Sa-Fire.

The Jackson estate confirmed that the "new" song had actually been written in 1983.

"The song was picked because the lyrics were appropriate because of the name Michael gave his tour," the estate said, referring to the singer's planned comeback tour This Is It. "We are thrilled to present this song in Michael's voice for the first time and that Michael's fans have responded in unprecedented numbers."

The song was released to great fanfare but only lukewarm reviews on Monday, four months after Jackson's death. Its release came in advance of the release of a similarly titled CD later this month and a documentary movie based on rehearsal footage for the aborted comeback tour.

The song opens with the words "This is it. Here I stand. I'm the light of the world. I feel grand."

"Falling in love wasn't my plan," Jackson croons. "I never thought I would be your lovebird."

Background vocals sung by Jackson's brothers were added to the track but otherwise the production dates back to the singer's 1983 recording session, Anka said.

The documentary is to give film-goers a look behind the scenes at Jackson's rehearsals for a sold-out series of 50 concerts in London that was to have begun in July. The theme of those shows was also to have been This Is It.

The song was expected to be the first of a long line of Jackson material that his label Sony and his family would make available as they sift through his unreleased work.

The singer of such hits as "Thriller," "Bad" and "Billie Jean" has again topped the best-seller lists since his June 25 death. Billboard magazine said Jackson sold 5 million albums in the week after his death in Los Angeles at the age of 50, after selling 750 million records during his career. His collection Number Ones became the best-selling album so far this year.

Anka, who rose to fame in the '50s and '60s as a pop singer, wrote and recorded such hit songs as Diana, Lonely Boy and Put Your Head on My Shoulder. He wrote lyrics for other singers, including My Way for Frank Sinatra and She's a Lady for Tom Jones.(dpa)