Michael Jackson has been told to put on weight ahead of his comeback shows in London this summer, according to reports.

The King of Pop is said to be 20lb underweight and also undergoing antibiotic treatment for a skin infection.

Michael is due to kick start his This Is It gigs at the O2 Arena on July 8.

A source told the Sun newspaper: “There are concerns Michael is too frail. He has been ordered to eat more but he refuses to and eats like a bird.”  

Despite the tabloid claims, a spokesman for concert promoter AEG Live said the Bille Jean singer was “extremely fit”.

Michael, 50, is currently rehearsing for the O2 gigs in Los Angeles.

He has not performed a full concert since he was cleared of child molestation charges in 2005.

But the singer is understood to be plotting an elaborate stage return, which includes animals and a special appearance from his children.

Michael Jackson - This Is It