`Frail` Michael Jackson was to lip-synch at O2 Arena

Washington: Michael Jackson, who was in poor health, was unable to sing and dance at the same time as he prepared for his comeback shows, new documents have revealed.

Shocking emails between executives at concert organisers AEG show that the King of Pop was set to lip-synch to old recordings at London`s O2 Arena, the Sun reported.

The connections will be used by the late singer`s family in their 25.7billion-pound lawsuit against the gig organisers.

They say pressure over the gigs contributed to his death in 2009.