The pop star has pulled all shows on her North American tour after an operation on her knee...

BRITNEY SPEARS has pulled out of a North American tour after having surgery on her knee.

The superstar was taken to hospital after she fell in New York (June 9) during the filming for the video for the song ’Outrageous’.

The singer has had problems with her knee before, and earlier this year had to cancel live appearances because of a similar problem.

Spears has been told she has to remain off her feet for six weeks, wearing a brace, before undertaking over two months of rehabilitation.

The tour was due to start later this month (June 22), ending in August.