Video of Michael Jackson preparing for his ill-fated comeback concerts in London has been unveiled for the first time.

It forms part of the official trailer to the forthcoming movie This Is It, which is released in cinemas next month.

The film has been created from over 100 hours of behind-the-scenes footage of Jackson as he rehearsed for his comeback.

This Is It has been directed by choreographer Kenny Ortega and will be given a limited two-week cinema release from October 28.

Jackson died on June 25 - just two weeks before his comeback was due to begin.

Michael Jackson - This Is It Trailer