A DANCER who worked with Michael Jackson says she expressed concerns about the singer's health as he prepared for a series of planned comeback concerts at Greenwich's The O2.

Dancer and choreographer Alif Sankey told a jury hearing a lawsuit filed by Jackson's mother in Los Angeles that the pop star appeared thin and unprepared for the demands of the shows.

She testified that a month before Jackson's June 2009 death, she wrote an email to tour director Kenny Ortega urging him to try to improve the singer's health and spirits. She says she never received a reply.

Sankey worked with Jackson beginning on his music video for 1987's Smooth Criminal and was an associate producer on the singer's planned comeback tour This Is It.

She is testifying in a negligent hiring trial filed by Jackson's mother against concert promoter AEG Live LLC.