Madonna was planning to join Michael Jackson on stage during his comeback tour.

According to her manager Guy Oseary, the Queen of Pop wanted to make a surprise appearance at one of Jackson's O2 arena concerts in London.

The dates were due to start in July (09) and the 'Material Girl' hitmaker was all set to be a special guest.

"A month ago Madonna told me she wanted to do a surprise performance at one of Michael Jackson's UK shows," Contactmusic quoted Oseary as stating on his Twitter.com blog.

Jackson apparently died after suffering a heart attack at his home in Los Angeles.

Madonna has revealed that she 'can't stop crying' over Jackson's sudden death.